Blake Griffin and Girlfriend Francesca Aiello Hit the Beach in Malibu

Blake Griffin stripped down to his niftiest trunks for a beach day this weekend, but might've been one-upped by his own GF's swimwear ... yeah, bikinis are kinda her thing.

The Pistons power forward hit up a beach in Malibu Saturday with Francesca Aiello -- founder of Frankies Bikinis -- whom he's been seeing since at least last month. Unlike their last 'Bu outing, this time they got in the water ... and showed off their killer bods.

Yes, Blake was looking good in his pink shorts -- but, truth be told ... Francesca seems to have the edge over him here. That just us, though.