Is it true Michael Phelps went to a party and swam laps for cash?

The New York Post says Mikey jumped right in -- when the gold medal Olympian pocketed $100,000 to hop in the pool at an L.A. party hosted by a TV network head honcho.

ABC says there's no need for Phelps to be a sellout. The eight gold medals Phelps racked up this summer equals an anticipated $100-million payday during his lifetime.