WordNet (r) 3.0 (2006):

snarl up
    v 1: make more complicated or confused through entanglements
         [syn: snarl, snarl up, embrangle]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "snarl up":
   ball up, bollix, bollix up, bugger, bugger up, complicate,
   confound, confuse, cook, embrangle, entangle, foul up, fumble,
   garble, gum up, hash up, implicate, involve, jumble, knot,
   louse up, mess up, mix up, muck up, muddle, perplex, pi,
   play hell with, play hob with, queer, ramify, ravel, riffle,
   scramble, screw up, shuffle, sink, snafu, snarl, tangle, tumble