I’m compiling a list of words meaning “incomprehensible”, or “incoherent” or “nonsense.” The definition I’m using is pretty loose, but I’m thinking of words like “balderdash” and “poppycock”. I’ve got 21 so far. Please help.
Are you going to let us know the 21 you already have, so that we don’t post duplicates?
Actually, no. I’m curious to see how many of them dopers come up with. It would be nice if everyone offered only one or two.
Horsefeathers.
Codswallop.
Bullpuckey.
Piffle
Jibberish
Claptrap
Wibble
Flim-flam
Hogwash
Mumbo-jumbo
Gobbledygook
Not sure if this one qualifies:
Tomfoolery
Codswallop! Fucking beautiful. This could be fun.
Tomfoolery, not so much. Please keep words down so we can get more people in. 
Cockamamie
Folderol
Bollocks.
A few more that don’t seem to have come up yet:
Hooey
Jibba-jabba
Baloney
Rubbish
Silliness
hokum
twaddle
Flapdoodle.
Malarkey.
Balderdash.
Bumf.
No one’s said bullshit yet? I call bullshit!
GIGO
Fiddlesticks
We always said razzle-dazzle when I was growing up, but I’m not sure if one of my friends invented that usage or not. I’ve never heard anyone else say it, but people know what I mean when I say it.
Bunkum.
Horseshit.
Tripe. Tripe is my favorite because its flexible as fuck if you want it to be.
Well that’s tripe.
I declare tripe.
Manishevitz, that’s some tripe.
You’re espousing tripe, again.
This isn’t a stable, clean up your tripe.
Very nice so far. I honestly didn’t expect to see a few on my list. “Twaddle”, for example. And I didn’t expect for “bullshit” to be so late in coming. On the other hand, how did I ever leave “malarkey” off? And while I had “horse hockey”, why did I never come up with “horseshit?”
As an aside, did you ever wonder why there are so many such slang words?
Tosh
Naff