He had a bad case of the runs.

The Bravest busted for allegedly pooping on a stranger’s lawn chair in New Jersey wasted his chance Saturday to defend himself against the stinky accusations.

“I know who you are, I have nothing to say to you. Goodbye,” probationary firefighter Joseph Cassano told The Post — before bolting inside the Staten Island home he shares with his parents.

This was controversy No. 2 involving the son of former FDNY commissioner Sal Cassano.

Back in 2013, the younger Cassano was forced to resign his city EMT gig after The Post exposed his racist and anti-Semitic Twitter account.

But Nigro took Cassano back and he graduated from the academy, in April.

The probationary fireman has been suspended 30 days, stemming from his incident in Lake Como, New Jersey.

He faces possible discharge, which could once and for all flush his FDNY career down the toilet.