Moderate-to-low zaniness, I’d say. I’m fine with improbable successes, but not absurdist breaches of the laws of physics/magic (i.e., a 25 on an acrobatics check while falling might enable you to grab onto something in the face of certain doom, but you won’t start flapping your arms and fly back up).
Now, when players start doing silly things “for the lulz,” that rubs me the wrong way. Humor is perfectly welcome at the table, but there’s a difference between that and a character doing something solely because the player thinks it’d be funny.
Edited to Add:
If we’re talking settings gonzo-ness (or gonzosity, if you prefer), for the longest time I went pretty bog-standard Tolkien. In recent years, I’ve really been trying to break out of that. I’ve become increasingly fond of high-magic settings, as they enable some neat ideas for me.
As far as Muppets go, yes, Gonzo was my favorite. And I dig Hunter S. Thompson’s writing, but not as obsessively as some.