1) While your SO is in bed with you, tightly hold the covers close to you to create a good seal that will prevent noxious gases from coming out near you.
2) Let one go. Silent but deadly is better as everyone loves surprises.
3) Slowly use your foot to raise the covers at the far end of the bed.
4) Let your foot drop. If done properly, "The Bellows" should give your SO a nice blast of your most recent work while leaving you protected and laughing.
NOTE: Punches in the arm as well as the well earned title of "you asshole" are a likely result
This was inspired by the Dutch Oven