Behold ... ASS SLAP REVENGE!!!
Shane Mosely's girlfriend took matters into her own hands yesterday -- dousing Ricardo Mayorga with water as a form of retaliation for that whole ass slap thing earlier this week.
TMZ Sports has the video ... showing Mayorga getting hit with the aquatic attack during the weigh in for tonight's big fight in Los Angeles.
Yes, we know ... it's definitely a shameless publicity stunt -- but it's funny. So watch the video.