The act of taking a shit on someones chest before during or after sex (can be used as a punishment, break up tactic or fetish act) Very similar to the Cleveland Steamer, but with the Boston Steamer, you also tea bag her with you nut-sack while taking the shit.
Bitch, shut your fuckin mouth, or i'll tape you to the bed and give you a Boston Steamer.
by AT Facials June 11, 2004
A Boston Steamer is 70's term named for a certain 1970's celebrity that liked getting his dick sucked while he took a shit. Hence, a blowjob while your shitting is called a Boston steamer.
After the concert the singer went up to the hotel room and had a groupie give him his favorite: a Boston steamer.
by Ehusserl April 29, 2010