look up any word, like no soap...radio:
 
1.
To prepare the bed for your girlfriend or spouse by trapping an enormous gas attack or fart under the covers just as she pull back the sheets to get into the bed. Like a Dutch Oven except it is a surprise attack.
Jim let go a huge gas barrage, under the covers, and tucked in the sheets to prepare a bed warmer for his woman.

Or,

As she pulled back the sheets and was overcome by the stench, she knew her Husband had prepared a bed warmer.
by The Dutch Auto Man November 12, 2007
79 25
 
2.
Term originating at Renaissance Faires used to describe a one-night-stand type relationship.
Did you see that girl with Aron? I bet she's gonna be his bed warmer tonight...
by kimberkid January 10, 2005
24 5
 
3.
A man or woman that a person keeps within a relationship for the sole purpose of not being alone; Company in bed at night and a sexual playmate. The bedwarmer doesn't always know it and is under the impression that the person actually loves him or her.
Ann: Why do you keep him if you hate everything about him?
Jane: I get lonely at night and I don't want to just sleep around with random men
Ann: So he's just like your bed warmer then?
by FlamingPsycho June 01, 2012
8 1
 
4.
An insulting word meaning a woman/man who lays in the bed of someone else after having sex.

You can use it and if the person isn't smart, they'll think its a cute little name.
John: I love you bedwarmer.
Jane: Awww, thanks boo!
by LovelyLadyOftheMoon January 14, 2011
2 4