Simon Cowell barbados jet ski Terri Seynour Boyfriend fans Clark Mallon Spread Pictures

Talk about friendly exes ... geez!

On Monday Simon Cowell was snapped heading down the beach in Barbados to go jet skiing, and he was joined by his ex-girlfriend Terri Seymour ... and her boyfriend, Clark Mallon, who is 15 years her junior.

Seymour has been dating Mallon since 2011, but that didn't stop her from sitting in Cowell's lap back in October after a wild night out. And no, the music mogul's pregnant baby mama Lauren Silverman was NOT in the car with the former flames when all that went down. Silverman is right on the cutoff for being too far along in her pregnancy to fly, but we find it interesting that she's not with Simon for the holidays -- if she is, she has yet to leave their posh hotel!