Terrell Owens -- Suspect in Starbucks Coffee-Throwing Caper (UPDATE)

Terrell Owens is a suspect in the most ridiculous battery case in 2015 ... and TMZ Sports has learned the alleged weapon was a Starbucks coffee cup.

T.O. was in a Brentwood, CA Starbucks Tuesday when a 28-year-old guy started screaming his name. An annoyed Terrell implored the guy to pipe down. The guy claims T.O. intentionally tripped him as he walked past the former football great.

Fast forward to T.O. getting into a Mercedes to leave, and then the loud talker screamed something. One witness heard, "F*** you, Terrell Owens." Another witness claims the guy said, "Bitch ass n*****."

According to cops, Terrell allegedly got out of the car and threw a paper coffee cup at the guy.

The 28-year-old called the cops and the paramedics, claiming he was injured. When cops arrived they noticed there was no evidence of coffee on the man's clothes ... and no evidence of injury.

Police are investigating. Seriously.

7:30 AM PT -- We spoke to T.O. and he says the situation was even more bizarre and menacing. He tells us the guy was following him and a female friend around the store, then followed them to their car ... and threw a cup of liquid INTO the car.

Terrell says that's when he got out and threw his empty cup at the guy. He confirms he absolutely heard him use the n-word.