Tie your sissy’s hands behind her back so she isn’t tempted to do anything disobedient. Unlock her caged little dicklet, maybe giving it a few swats for good measure.
Now have her bend over the bed with her legs spread a bit. Situate yourself behind her on the floor, with a ruler or similar implement handy.
With one hand, firmly grasp at the base of your sissy’s clit and balls. With the other hand, start giving her the stroking along her short little rod. Her desperate moans should be fairly entertaining. Allow yourself a little laugh.
Now comes the tricky part. Chances are, your little slut is going to want to spurt her tiny load pretty quickly, so you shouldn’t have to wait long. Watch for her ass cheeks starting to clench involuntarily. As soon as the first signs of her sissy orgasm start, immediately stop stroking her shaft and switch over to the ruler.
With your grip with the other hand still firmly holding her genitals in position, start giving firm swats with the ruler to her unfortunate little balls as she spurts her gooey mess. If you time it correctly, she should experience an almost perfectly ruined orgasm, as the shooting pain from her testicles overwhelms the sensation of cumming.
And then of course, she must lick up her mess, get cleaned up, and clitty cage goes back in place.