Because he heard the ref was blowing fowls.
Explanation: The phrase “blowing fowls” serves a dual purpose. On one hand, it refers to a referee making calls for fouls in basketball, which is a common occurrence during the game. On the other hand, the phrase can be interpreted as a humorous reference to oral intimacy involving fowls, playing on the sound of “fouls” and “fowls.” This layered joke combines sports terminology with a cheeky twist, making it both playful and a bit risqué.