What exactly is a douchebag?
are you asking about the literal meaning of the word? I've no idea but have similar associations as you. Anyway, I've picked it up on a F1 forum where it is frequently used, in relation to the drivers, in contexts where a Pole would just call somebody "dupa wołowa", so I've thought it to be an appropriate translation :)
Pipa, pipka or cipa are words for the female sexual organ so "męska pipa" - a male pipa - denotes somebody who's ineffective, undecided and generally shows no character - just like dupa wołowa.
Albo rybka, albo pipka. How about that one?
that's an either-or situation, similar to "albo rybki, albo akwarium" - either the fish or a fish tank