Kobe Bryant's interpretation of a topless party is WAYYY different than ours.

TMZ obtained photos of the Team USA star at an afterparty in Barcelona earlier this week ... hanging out with two hot chicks ... sans shirt.

One source close to Kobe who was at the party tells us Bryant was FORCED to strip down because "someone spilled an entire drink on him ... his shirt was soaking wet."

We're told Kobe sent someone to get him another shirt ... but he's jacked, so no one complained.

According to our sources, both women in the photo had their significant other with them at the after party (one husband, one boyfriend).

Kobe had one helluva time in Spain ... he was pictured chattin' with two different ladies at a nightclub earlier that evening. Go USA.