With forty episodes under its belt, Sgt. Frog is finding it rather more difficult to take us by surprise. Which is not unexpected, but nonetheless bad news for the series' laugh factor. Though not as bad of news as it could have been. Even if it can't ambush your funny bone the way it once did, Sgt. Frog still has enough invention in it to secure it a place as one of the more consistently funny long-running comedies around.

At this point in the series any reasonably attentive viewer, and most inattentive ones, will know everything there is to know about it. Its basic structure is metronomically invariable: Keroro and his platoon hatch a hare-brained plan (to make money, conquer the world, get Natsumi to stop beating him) that goes well for a while before self-destructing in some spectacularly Keroro-abusive way—all within the compact confines of a single half-episode. The series has finished introducing new cast members, who have in the interim grown so familiar that a child could map their relevant personality quirks. And its reliance on holidays and Japanese traditions for in-episode plot structure has become so total that it could easily be sub-titled "An Alien's Guide to Japanese Culture."

In short Sgt. Frog has become hugely predictable. Each episode is ruled by laws that are as immutable as any that Newton formulated: Any serious turn will be undercut at the eleventh hour by a gag that zeroes out any growth or change. No character ever violates the sanctity of their basic personality. Keroro always gets his comeuppance. And there is nothing in the universe that cannot be resolved in the space of a single episode. Taken in conjunction with the premise's loss of freshness, this has the inevitable result of making the series less uproarious than it initially was. Its family-friendly messages of friendship and responsibility take point ever more often, extending into episode-long riffs on laziness and the bonds that tie families, even makeshift ones involving froggy invaders, together. Gag density goes down and those that remain, particularly the ones reliant on familiar character shtick, fall flat more often.

And without tears of laughter to blind us, the show's major shortcomings are only too obvious: the repetitious nature of it, the sometimes uncomfortable tension between its wholesome messages and frivolous treatment of them (particularly in English), the way it occasionally lets Keroro torture Natsumi so long that it gets weirdly sadistic.

But for all that, the series is still able to beat back senescence with its sense of humor, breaking out enough little tweaks and off-the-wall comic inventions to keep its entertainment value largely intact. Jokes are allowed to cross episodes to become short-lived running gags (a privilege not extended to the plot), an approach that reaches its apotheosis in a silly winter sports showdown in which two essentially unrelated half-episodes are joined together by a series of amusingly overlapping disasters. The series' eye for hilarious sight gags (Keroro's confection-barfing dango machine) and bizarre parody (Keroro casting himself as the Little Match Girl) remains unerring—enough on its own to ensure that, even with their success rate sputtering, a sufficient number of jokes smack the funny bone upside the head to keep the show consistently fun.

As the series' focus shifts a bit away from pure humor, it experiments more with other facets of its signature look. The Valentine's Day episode cranks the show's cuteness up to warp factor ten, the final episode dabbles in melancholy atmosphere, and more than one episode channels the series' frenetic energy into sci-fi action that wouldn't be out of place in the continually-referenced Gundam. ...If you discount the fact that it is performed by ridiculous frog aliens. And therein lies the series' genius. The sight of frog aliens doing galactically dumb sh** never gets old, be it Keroro posing as a "lovely and cute" kappa, Giroro going colonial, or "Magical Girl Kululuko." Indeed, such sight gags are the series' backbone. It may be glossy and unusually well animated for an endless comedy, but it's that eye for the composition, execution and timing of sight gags, as well as the unflagging energy with which it throws them at you, that elevates Sgt. Frog above its peers. Well, that and the return of the Kogoroader.

Aside from kicking the series' target demographic up a couple of years in age, Funimation's erm, reinterpretive dub also maximizes the series' humor with a kind of ruthless single-mindedness. Jammed with self-referential jokes, pop-culture references and its own original brand of character humor until it can jam no more, the English "reversion" is consistently hilarious in a way that the original series sometimes isn't. It has an energy and life that the company's more conservative dubs sometimes lack, fuelled by a continually brilliant turn by Todd Haberkorn (as Keroro) and consistently enthusiastic work from a team of veterans who manage to ape their Japanese counterparts even as they take a wrecking ball to their personalities and dialogue. It can still feel a little arch, and does not handle the serious episodes well (it generally tries to steer them into comedy territory with massive doses of self-derision), but it is undeniably fun.

Extras: another word for "the same-old." The clean versions of all of the new ending sequences as well as the old one are nice, allowing an opportunity to enjoy text-free the energetic pop (and drawing—don't ask) songs that cap off each episode. All of which are a seamless part of Saeko Suzuki's thoroughly goony score.

Consistency is good. It allows for succinct summations: If you liked what came before, you'll like this. Flagging funny factor and all.