David Guetta -- Tiesto Crashed Into My Dock With a Yacht ... And I Can't Stop Laughing

Rockstar DJ Tiesto just showed us how to get a laugh out of a multi-millionaire -- simply total his South Beach dock by smashing into it with a yacht!

Sources close to the situation tell TMZ ... Tiesto and crew -- Martin Garrix, and LIV owner Dave Grutman -- went to scoop up David Guetta in Grutman's 55' VanDutch yacht. Y'know, typical Wednesday stuff.

But as they approached Guetta's dock, the engine stalled and they couldn't stop the boat from barreling into the dock. Don't worry ... we're told nobody was hurt, and even the boat survived without a scratch.

Guetta's response -- laugh hysterically, jump aboard the yacht, and head to a party.

We're told it's gonna cost about 30k to fix the dock, and Guetta won't make Tiesto pay for it. As for why they all laughed it off -- Tiesto, Guetta, and Garrix all command about $300k to $500k for a single gig.

#richpeopleNOproblems