Theo James has clearly ended up on some s****y first dates … ’cause the guy says he once went out with a girl who ended up taking a dump in his bathtub!

The actor recently sat down with Entertainment Weekly for a panel discussion and played Two Truths and a Lie — a game where a person says two true statements and one lie and others guess which is which — and he said a woman once left him a brown reminder of their time together.

The way Theo tells the story … it was back during his university days, and he and this girl hit the town before heading back to his place where they had some “fun” — you can probably read between the lines on your own.

Theo says his lady friend left in the morning … but, when he went to his bathroom, he found a gift waiting for him in his bathtub — a “small turd” as he puts it. Theo says he thought the date went well, so he was a bit miffed to find what she left behind.

No word on how he fished the Hershey’s Kiss out of the bath … but, sounds like he’s laughing about it all these years later.

BTW … not the only bodily functions story Theo’s recently told — revealing earlier this week he actually had a bottle of urine thrown at him while onstage playing with his band. So, the guy’s dealt with more than his fair share of excretions.

Anyhoo … sounds like no second date between Theo and this mystery woman — which is for the best, ’cause who knows what could happen on date Number 2!!!