In Rio is usual to say 'Migué' to this effect, and when somebody have a hangover and is hastily going to the loo to throw up, they say that the guy is going "chamar o Raul" (To call Raul).    This 'Migué' also reminded me of an expression that is 'passar um/dar um migué' in alguém (to fool someone/give any excuse to get away with some fib), for example. The guy comes at home at the small hours tiptoeing and his wife is awake, he have to give a 'Migué'.

    PP.