trip means weird? It occurs in the movie Forrest Gump. I think Jenny is trying to imply that Forrest has have made some journey to obtain that uniform.
EXT. WASHINGTON D.C. - NIGHT Forrest and Jenny walk past the White House. Protesters hold a candlelight vigil behind them. They walk in silence. Jenny touches Forrest's uniform. JENNY That uniform is a trip, Forrest. You look handsome in it. You do.