
Twitter sure seems to think so.
i dont think the oregon zoo knew what they were doing when they booked mac demarco, he just pissed his pants on stage
โ nickelback.jpeg (@hittingonjesus) September 10, 2017
Mac Demarco peed his pants onstage tonight
โ Hanna Gentile (@probably_hanna) September 10, 2017
mac demarco just peed his pants on stage
โ frank ocean fan acco (@xochcontreras) September 10, 2017
Mac DeMarco straight up peed his pants during tonight’s performance and I kinda liked it
โ Charlianne (@Charlianne21) September 10, 2017
Mac Demarco deadass pissed his pants on stage
โ SRA (@sarahjah00) September 10, 2017
Today I watched Mac Demarco piss his pants
โ windows startup nois (@cubangelion) September 10, 2017
DeMarco plays in Seattle tonight. Gallagher-style protective gear may be advised.

When ya gotta go, ya gotta go.
From my perspective under the stage, he talked about it, but did not do it. If he actually did, teenaged girls have become much, much more forgiving of the behavior of their idols.