Hammock Foam Roller
You don't want people to think you are a tight-ass so make sure you stretch out your butt! In all seriousness though, if you sit throughout the day your butt and hips, especially your piriformis muscle, can become incredibly tight so stretching with the foam roll is a great way to release some of that tension.
Start by sitting on the foam roll with your arms underneath you and legs in front of the foam roll. Bring one leg over top and roll on top of the roller back and forth to put pressure through your butt and hips as you roll, especially on the side where your leg is crossed over from. After about 30 seconds, switch to the other side and repeat. It might not feel good right away but you will thank us in the long run!