When my wife refuses to give me a BJ. I get up hours later and masturbate. Then pour it all in her mouth wash container, it's solid white plastic so she never see's it cuming.
When we were dating, I moved in with her. When she refused sex I could get up hours later and masturbate in the hallway. I would cum on the wall. It left nasty brown streaks the next day. She thought our male cat was spraying and got rid of him.
When she gets pissed at me for not doing a chore fast enough. I wait till she leaves the house, then peal back her side of the bed, and ejaculate on her sheets. By the time she goes to bed the sheets are stuck together and crusty. She's never complained. But I can hear it separating when she gets in bed.