People in Boston, particularly those with a strong Boston Accent will say “Wicked Pissah”, which is Wicked Pisser but the Boston Accent doesn’t really pronounce the “r’s” so it becomes Pisa. Basically it just means that something is really awesome. You can say it about a person or a thing. It’s also somewhat of a joke at this point because it’s a cliche Boston Accent thing to say. So it’s ironic to say but also not ironic in another sense.

Informant is from Boston.