A retiree visiting his son on Long Island for Thanksgiving got a smelly — and nearly deadly — surprise yesterday when a section of lawn gave way, dropping him neck-deep into a cesspool.

Eduardo Matos, 71, from Puerto Rico, fell into the sewage at around 11:30 a.m. outside his son’s Deer Park home.

“I was calm . . . If you panic, that s- – – will suck you right in,” he said.

Matos managed to keep his head above the muck until he was pulled out by his son and daughter.