Mystery Date (1991)

Tom McHugh quickly learns that his perfect big brother Craig isn't all he's cracked up to be while on a night on the town with the girl next door, during which Tom is harassed by unpleasant strangers, threatened by mobsters, pursued by police, attacked by an irate florist, accused of murder, and has his date kidnapped—all because everyone thinks he's Craig...and the classic 1959 DeSoto Firesweep he borrowed off his brother has two dead bodies in the trunk.

Comedy, Romance