Very mild language, with the occasional bleeping out of swearing for comedic purposes.
In Lazy In Space, the swearing is only in 4, 3 or 5 episodes. They're all censored, though still a little strong.
In Golden Eyes, a human fish flips of Wesley. It's censored, but it doesn't mean you can't see it.
A running joke in the Netflix version of the show: PuppyCat screams, "I'm not a baby! I'm a big-ass man!" This is said in subtitles (as he speaks random autotuned gibberish) and it was not in the original YouTube show.
Infrequent use of mild to very mild language; "hell", "crap", "crotch". Some name-calling.