Have her invade sister's mind

"I have an idea. I want you to enter Anita's mind, learn what gets her off, and if you can, make her dream what we just recorded."

"How kinky. I can easily do that. I have a whole bag of tricks to try out. I presume you want it vivid enough that she might have doubts that it was just a dream."

"Exactly. Right now I might feel awkward looking at her after what we just did, but if you do that, it would amuse me to see how she looks at me, thinking of her dream."

"Consider it done. No matter how perverted you get, I'll support and encourage you through it all."

As a mass of slime, she slinks under your door, then hers, and her room fills with the gaseous form of Eileen, and soon enough her dream of being head cheerleader is replaced with eventually giving head.

While that's going on, you decide you need a shower, especially with what you've been doing lately. You make it as quick as possible to do even more. You hear a knock on the door. You get the mischievous idea to answer the door with your towel loose enough to fall, hopefully it's Anita and she'll finally show you an embarrassed side to her. If it's Eileen telling you about her accomplished mission, she'll consider it her reward. You barely wrap the towel around your waist to cover your boner and open the door.