Wow. Shark's referring people to my walkthrough... I feel honored. XD
Susan, incase you're still lost, once you tickle her arms and stomach to make her loosen up and drop the bra, then you will automatically drop the feather.
Sheed, I assume you're at the part where Angela is down to her bra and is holder her arms across her breasts. You have to click once on her breasts (if only to get denied, but it gets better), then click and rub (circular motion) her thighs. There's no real graphical sign that you're doing this right, other than the pleasure bar which will rise.