A man made a splash at an Upper West Side bar when he interrupted a beer pong game to smash a pitcher of beer over a player’s head, cops said Monday.

Kenneth Hernandez, 39, was tossing ping pong balls with his friend, Rodolfo Arguelles, 54, at Jake’s Dilemma around 6 p.m. Sunday, when the violent jerk hit him with the pitcher, according to police.

Hernandez tried to stop the attacker from pummeling his friend and got whacked with an unknown object, causing bruising and swelling to his forehead, cops said.

The unnamed attacker bolted from the gritty pub, which features a pool table and video games on Amsterdam Avenue near West 81st Street.