I have never heard of that either. In British vulgar slang, to have a slash means to have a piss, perhaps particularly when it is done al fresco and/or drunk. Could you perhaps have mistakenly taken someone talking about a slash in that sense to have been talking about vomiting?
I doubt it seriously, but you can never tell with stuff like that. It was quite common in my boyhood days in Alabama. As with many such terms they come and go in a short span of time. It gave way to hurl, barf, and others that I’m having trouble recalling because they didn’t last that long.
But it’s like so many of those slang expression that Brits and Yanks have differing meanings for that when you hear the word, let’s say “fanny” for example, it can take on a connotation even when you realize something else is being meant by the speaker.
But I must remember to use your word next time I’m writing yellow snow.
Y’all might be curious what brought on this idea. I was about to reply to the thread about “emotional reponses to movie scenes” (or whatever) and was prepared to use “slash” in my reply. Then I wondered if it would even make sense.
Heh…I remember when Roger Daltrey was doing a promo interview for the Who’s (sad) Superbowl performance. He said something along the lines of “Well, it is halftime, most of the blokes will probably be off having a slash.”