the act of having intercourse without the other partner knowing about it at first commonly confused with rape your partner may scream NO!, Stop!, and Dont! but a kind reply of Surprise will let them know what is happening.
After Diane's Birthday party she was so wasted Jake totally surprised sex'd her, boy was she pissed the next morning.
Q: Would you try to stop her if she tried to rape you?
A: No I happen to be a fan of surprise sex I love gifts