Blue balls

[teased_denial]

I think that one of the hardest part of denial is blue balls.
One of the best way to cause it, is to tease and then lock a tight chastity cage.

If you don't have a chastity cage, what are your favourite ways to cause blue balls to your slaves, or to yourself?
How often do you tease/edge/stroke and how long?
I think that a good way is also to tease while the slave has his cock and balls tied up.
What do you think?