WordNet (r) 3.0 (2006):

horn in
    v 1: search or inquire in a meddlesome way; "This guy is always
         nosing around the office" [syn: intrude, horn in,
         pry, nose, poke]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "horn in":
   barge in, break in, break in upon, burst in, busybody, butt in,
   charge in, chisel, come between, crash, crash in, crash the gates,
   creep in, crowd in, cut in, edge in, elbow in, encroach, entrench,
   foist in, fool, impinge, impose, impose on, impose upon,
   infiltrate, infringe, insinuate, interfere, interlope, intermeddle,
   interpose, intervene, intrude, invade, irrupt, make, monkey with,
   obtrude, press in, push in, put on, put upon, rush in, slink in,
   slip in, smash in, sneak in, squeeze in, steal in, storm in,
   tamper with, throng in, thrust in, trench, trespass, work in,
   worm in