Jonathan Martin -- Gangsta Party in the Suburbs

Jonathan Martin proved you can be anti-bullying AND gangsta at the same time ... by partying his ass off on the mean streets of Santa Monica, TMZ Sports has learned.

The former Dolphins OT was out Friday night throwing up a 'W' outside MAIN Nightclub with a fan named Tym from Compton.

The pic was posted on FB with the hashtags: #NOBULLYING #F**KINCOGNITO #WESTCOASTS**T

According to Tym, Martin and his entourage hung out at a house party, drinking straight through the night ... and most importantly ... never uttering Richie Incognito's name.

We've reached out to Jonathan ... no word back yet.