'TMZ After Dark' Goes Double Trouble in Hollywood With Two Party Buses

"TMZ After Dark" doubled the chaos this weekend -- two buses, twice the drama, and zero doubt we’re the wildest party rolling through Hollywood!

Check it out ... OFB Yung from Cali Swag District, Klypso, and The FiNATTiCZ pulled up and set the vibe ... downing those shots, riding mechanical bulls like pros, and turning all the way up for a party-goer's birthday ... all fueled by Monster Energy!

The bus was bumping Cali Swag District's "Teach Me How to Dougie," and "Don't Drop That Thun Thun" by The FiNATTiCZ ... and OFB Yung even taught everybody onboard how to Dougie!

Looks like the crew really bonded during the chaos ... they ended up linking arms crossing the street like a rom-com cast, and dove straight into their feels, belting out Vanessa Carlton’s "A Thousand Miles."

Klypso also used the night to tease his new track ... all while everyone chugged their Monster Energy, the official fuel -- and sponsor -- of the night’s madness.