Kal Penn -- My Flight was Grounded Over Crapper Emergency

Kal Penn had a mid-air bathroom emergency during an American Airlines flight earlier today ... as in, the toilets BROKE at 10,000 feet ... and the pilot decided to ground the plane ASAP.

The "Harold & Kumar" actor was aboard a flight from LAX to Dallas when something went wrong with the plumbing ... so the captain decided to make an unscheduled landing in Albuquerque to avoid a potentially putrid situation on-board.

Once they touched down in New Mexico, Kal tweeted from the runway ... "toilet overflowed." He added, "My 1st emergency landing cuz of poop. Kinda funny kinda not."

A rep for AA explained, "The lavatories were inoperable, so we landed in Albuquerque briefly to service them, for the convenience of our customers. We apologized to our passengers for the inconvenience."