Very good trope: Cartoon characters having grown long beards to signify a lot of time has passed, regardless of how nonsensical it is for them to grow one.
Even better trope: It turns out it’s a fake beard they’re wearing just because
Absolute best trope: It turns out a comically short amount of time has passed (like five minutes or something)
My favorite execution of this was in chowder when they we’re waiting in an elevator and when it opened up there were skeletons with beards covered in cobwebs and they immediately move it out of the way and are like “this elevator was such a great place to store the skeleton sculptures of ourselves”