Edging: keeping yourself on the brink of coming but not actually getting there (yet)... I don't think there are many things out there which are more erotic, agonising or delicious.
After all, the best things cum to those who wait...
Even better is when it's done to you.
Picture it... You're nearly there. You can feel yourself tense, the sensations are building, you're gripping the sheets and you're so, so close...
He's watching you intently, noting every nuance in your expression, hearing every gasp and moan as you start to beg him for permission - to please let you come, please, please, you'll do anything - and there it is: that flash of a sadistic glimmer in his eyes even as his fingers/dick/whatever the fuck is getting you off right now don't ease up,..
Your body obeys even as your first thought is of what will happen if you don't... if you can't help yourself, if you lose control.
That only makes it worse - that threat of punishment - but you manage to hold off, to exert every last ounce of self control you possess - and then...
...it starts all over again.