The act of ejaculating upon the bald head of a female with cancer, after she removes her wig and informs you that she has no hair. The encounter is rarely pleasant, as the male assumes he is set to fornicate with a female having a normal appearing, hair-laden head. Traditionally, the female, expecting that the foreplay will turn into intercourse, will remove her wig and ask the male if he would still like to have sex with her. The male, quite perturbed yet not wishing to hurt her feelings, agrees to allow her to perform felacio upon him, and will then subsequently ejaculate upon her bald head, creating the Conehead Sundae.
Edgar: "Hey Mike, did you end up fucking that blonde chick you went home with last night?"
Mike: "Hells no. Just as we were about to fuck, she told me she had cancer and took off her wig. I told her to suck my dick and I made her a conehead sundae."