A "pop stand" is another word for a Soda fountain, which was a place where you went for sodas (Soda Pop) and milk shakes and sometimes a hamburger after school. When a group of guys got bored of just hanging out, someone would say, "Let's Blow this pop stand", which meant "let's get out of here."

The origins couldn’t have been earlier than the 1920’s. The San Francisco invention of the Popsicle was in 1924. “Let’s blow this joint” (leave this less than interesting place) may have been first and later the many variations including "Let's blow this fire-trap" or “Let's blow this popcorn stand”. In some parts of the U.S. a soda shop was called a pop stand so the phrase may have originated with “let’s blow this pop stand”. http://www.english.wesli.com/cgi-bin/webbbs/slang/index.cgi?read=700 let's blow this Popsicle stand, pop stand, lemonade stand, taco stand, hotdog stand OR this fire trap. "Blow" in the sense of "damn" or "curse" was fairly common in the UK up until about 50 years ago - I remember my mother when surprised or irritated using "oh blow" undoubtedly as a euphemism for some swearword exclamation. I imagine it originally comes from a wish for the offending issue to be blown away - possibly to Hell - though i have no evidence of such. "Blow this for a lark (or laugh)" would still be understood here, though we'd be more likely these days to use "screw" rather than "blow". We might even say "screw this for a game of soldiers". "Blow" in a pejoritive sense has of course recently got a new lease of life, courtesy of US English from what I understand, as in "let's blow this popsicle stand" or even the more vulgar "that blows". As a side note, and to jump eagerly onto one of my favourite hobbyhorses, Terry Pratchett is of course one of the finest writers writing today. Well...in the U.S. "blow" does mean leave. "Let's blow this firetrap." But it also means oral copulation. http://www.phrases.org.uk/bulletin_board/18/messages/319.html http://en.wiktionary.org/wiki/blow_this_pop_stand http://bits.westhost.com/idioms/id80.htm