You guess you can have a lot of fun with this doll...
You rip off the disco hairs and put the hairs of a Barbie doll that your sister forgot, on the doll. You grab 2 tennis table balls and put them on the chest of the doll and they fuse with the doll to form large breast. Lastly, you rip off the doll's penis and a vagina somehow forms on the doll.
You look at your roommate and see that he became a sexy girl with huge boobs but then, you realise your mistake : his mind didn't change. Your roommate was searching why his hairs became grey and disco and while doing so, he saw you play with the doll... You fear his reaction.