McConaughey Taps Ass -- Literally!

Matthew McConaughey taps actor pal Adam Rodriguez‘s ass (literally!) while playing football on a Malibu beach on Saturday.

Matthew is in “party mode” since he will be celebrating his 38th birthday today (Sunday) with friends.

Rodriguez, 32, plays fingerprint and drug identification expert Eric Delko on CSI: Miami. Matthew‘s Brazilian girlfriend Camila Alves was also seen on the beach playing paddle ball.