An unlucky Brisbane man has been robbed of his wallet, car and motorbike and allegedly threatened with a rifle, after an online date gone very wrong.

The 23-year-old met a 24-year-old woman on Plenty of Fish, and invited her to his home at Shailer Park on January 25.

Instead of a date, however, police allege the woman stole the man's wallet, car keys and his vehicle - and, in a series of increasingly unfortunate events, the man was also threatened, his flatmates were beaten up, and his motorbike was stolen.

The woman allegedly stole the man's vehicle and wallet on January 25. He reported the theft to police, and they found his Ford Falcon ute a few days later later following a crash.