Grand Opening

He wants you to rig a car with a bomb at 8-Ball's, then use it to blow the place to kingdom come.

A Major Malfunction

The Idaho which Jonnie wants you to use has been badly damaged already, so you've got to get to 8-Ball's and back without wrecking the car completely.

Get in the vehicle and make your way North East towards 8-Ball's bomb shop.

When you arrive, a guy called Slick will tell you 8-Ball's on the run for some reason, and explains how to use car bombs. Push A+B together when in the vehicle to arm the bomb, then once outside the car, select the detonator weapon and press A to trigger the explosion.

Make your way back to the bar where you'll find the target disco across the street, again being careful not to totally destroy the car.

Murder On The Dance Floor

Once you arrive, park the car in front of the disco, arm the bomb, then get out and blow it up. The cops'll be onto you soon afterwards though, so you'll need to lose your 3 star wanted level. Either head to your nearby hideout and use police bribes (if you've done at least 10 vigilante missions), or just go around collecting police bribes, or head directly to the Pay 'n' Spray. Either way, once you're clear of the cops, Jonnie will want to see you back at the bar.

Mission Passed!