balloon room, n. — Green’s Dictionary of Slang

balloon room n.

[like the SE balloon, marijuana smokers get high adj.¹ (3)]

(US black) a place where people gather to smoke marijuana.

1944

‘Jiver’s Bible’ in D. Burley Orig. Hbk of Harlem Jive.

balloon room without a parachute (n.)

(US black) a disappointment, a let-down, esp. a place where one has been promised a smoke of marijuana but which, in fact, offers no supply.

1941		D. Burley N.Y. Amsterdam Star-News 19 July 13: Then when my peeks dig the range, I latch on that I’m in the ballroom without a parachute.
1944		D. Burley Orig. Hbk of Harlem Jive 65: Then when my peeks dig the range, I’m booted that I’m in the ballroom without a parachute.