Green’s Dictionary of Slang

1. (US) to vomit.

1977

(con. 1969) M. Herr Dispatches 27: You were pissing up everything but your fucking toenails [...] don’t you tell me you weren’t scared, man.

2. to get drunk.

2005		J. Salazar Legion of the Lost 151: I spent a tenth of what other legionnaires threw away on drink by pissing-up in the hostel before heading out to the bars.
2006		B. Matthews Intractable [ebook] They usually pissed up when they both got paid.

3. see piss off v. (2)

4. see piss on v.