How to get rid of cellulite on thighs and butt? I'm a guy.

Rare in guys. In men, cellulite is rare because a major contributing factor is estrogen and an abundance of estrogen receptors in the areas where cellulite is found in women. Most guys that have cellulite have high estrogen levels. You should get those checked and addressed, otherwise the same treatments that apply to women to reduce the appearance, will apply to you as well.
Tough problem. This is a very difficult condition to treat and present options are generally short lived or only offer a partial correction.