Well, there is an obvious pose you can do for us.
Wrap the string around the base of your tits, building forward until you have at least two inches of 'wrap' on each one.
Wrap them as tight as you can.
They should be nice and proud now - show us how they look.
...now peg your nipples, and let's see that.
Now sit there for 20 mins as they swell & ache.
Show us how sore they are.
Take the pegs off your nipples, and rub them better - show us how perky you can get them.
Peg them again, and let's see that too.
Think you can manage that for us?
Sound like 'fun'?
Any questions?