When two lovers fall asleep or cuddle whilst one is penetrating the other. No thrusting is involved.

Originates from the Yahoo Answers question featured on My Brother My Brother and Me (9-12-2011).
It is impossible to perform swaddling for more than 30 seconds. If you can, you might be with the wrong gender or person.
by Stocky Gentleman September 12, 2011
A sex act when the man puts his penis into the woman's vagina and then they simply fall asleep for the remainder of the night.
Popularized by Griffin Mcelroy from MyBrotherMyBrotherAndMe
"I had the strangest dream, then I remembered Griffin and I were swaddling last night."
by GriffinMcelroyLover September 12, 2011
The act of a man falling a sleep with his dick in a woman's vagina. Swaddling has become a sexual sensation, as well as cultural, largely in, though not limited to, countries on the northern hemisphere.
by ThGy007 September 13, 2011
When a man and woman go to sleep after having sex with the man remaining inside of the woman.
After a great night, T and his girlfriend spent the night swaddling.
by forevercitrus82 September 13, 2011
And act of cuddling in which the gentleman's phallic device is inserted into the respective hole of his companion and then they proceed to go to sleep.
"Yo me and my girl just swaddled last night. Best sleep I've ever had"
by TheSlickPatriot September 17, 2020
When you sleep with your penis inside a girl for an entire night. As defined by Griffin McElroy in Episode 71 of advice podcast My Brother, My Brother, and Me. A resolution to the "chronic weiner coldness" malady.
Justin: "Hey, Debbie and I have fun night last night. We went and saw Contagion, got some great Thai food, and then I fell asleep with my weiner in her."
Griffin: "Oh that's called swaddling, I didn't even know - I thought we invented it. It's the new sex sensation that's sweeping the nation."
by commissionercrotchbuttons September 15, 2011