A bumbling birthday boy spent his big day in the clink for allegedly cracking a “bomb” joke that went down like a lead balloon.

Mack Bjorn, of Reno, Nevada, was on the jetway for his flight from Fort Lauderdale to San Francisco on Saturday — his 27th birthday — when he “joked that the TSA had missed a bomb in his bag,” WPLG reported.

When a flight attendant confronted Bjorn about his poor choice of words, he allegedly doubled down and “reaffirmed that the TSA missed the bomb in his bag,” according to a police report.

Bjorn was escorted from the area and placed under arrest.

Authorities found no bomb on him.

A Broward County judge found probable cause to charge him with making a false report of a bomb, arson or weapon of mass destruction, a second-degree felony.