Usain Bolt -- At Least One Athlete's Getting Paid at USC

The Usain Bolt world tour has touched down in South Central ... with the fastest man on the planet hitting the track at USC -- but unlike the other athletes on the field, Bolt was getting paid to be there.

We're told Bolt was shooting a commercial for Puma -- which required him to work out on the track and use the facilities at the University of Southern California.

When the cameras were off, Bolt chopped it up with a bunch of the student athletes ... including sprinter Andre De Grasse (pictured above left) ... the premiere 100m and 200m sprinter in the country.

Is Bolt sizing up his competition?

Also pictured, SC football player/track star Adoree' Jackson -- the PAC-12 defensive freshman of the year -- he's also super fast.