Green’s Dictionary of Slang

blow it out your ass! excl.

also blow it! blow it out! blow it out of your bag! blow it out your barracks bag! …B-bag! …butt! …footlocker!
[SE blow + ass n. (2)/butt n.1 (1a)]

(orig. US milit.) a general excl. of derision, contempt or dismissal of the previous speaker’s statement.

[US]P. Kendall Dict. Service Sl. n.p.: blow it out of your bag . . . refrain from talking, if you will be so good!
[US]J.W. Bishop ‘American Army Speech’ in AS XXI:4 Dec. 243: Blow it out your ass. This, used in lieu of ‘nuts,’ etc., or sometimes as an urgent invitation to shut up [...] In print it is softened to ‘Blow it out your footlocker’ or ‘Blow it out your B-Bag.’.
[US](con. 1944) N. Mailer Naked and Dead 33: Red, you can blow it out.
[US](con. 1943–5) A. Murphy To Hell and Back (1950) 104: ‘Saw them buzzards with my own eyes.’ ‘Oh, blow it.’.
[US](con. 1948) G. Mandel Flee the Angry Strangers 398: Blow it out your ass, Stoney!
[US]F. Paley Rumble on the Docks (1955) 137: Aw! Blow it out, Sully. You think —.
[US] in Randolph & Legman Ozark Folksongs and Folklore (1992) I 137: Tiddly-i-ai; shit, piss & corruption! / Blow it out your barracks bag!
[US]R. Graziano Somebody Up There Likes Me (1956) 168: ‘Blow it out your ass, Prude,’ I said.
[UK](con. 1943) A. Myrer Big War 168: Ah, blow it out, Mungo.
[US](con. 1950) E. Frankel Band of Brothers 62: ‘So knock it off!’ ‘Blow it out your butt!’.
[US](con. WWII) R. Leckie Marines! 37: Blow it, wise guy.
[US](con. 1940s) G. Mandel Wax Boom 276: Blow it out your ass, Lieutenant!
[US]L. Heinemann Close Quarters (1987) 257: If you don’t like the way I eat, blow it out yer ass.
[US]H. Rawson Dict. of Invective (1991) 53: Blow it out your barracks bag (or your B-bag or your footlocker) is a common way of cutting off anyone who is spouting a lot of malarkey. (In its original form, from World War II, this expression appears as blow it out your ass.).
[Aus]R.G. Barrett White Shoes 75: Go blow it out your ass motherfuckers.
L. Kohn Shadows of Rage 24: Blow it out your ass you stupid son-of-a-bitch!
D.N. Sanders Valley of Hope 496: Blow it out your ass, Sherrard. I’d sooner give the IRS my Swiss bank account number than give information to you.