Do It.

You unwrap the mask from around your cock and hold it up to her butt.

It only takes a few more moments before the floodgates open. What seems (and sounds) like a huge cascade of semen floods out of her butthole and into the inside of her mask. It's even thicker than the load you just released into her panties, and the nasty thick grey sludge smells rather strongly of butt.

What the perfect concoction to thoroughly saturate her face mask with.

Now justice has truly been served.

You wait a while for all the little extra spurts that come a bit later, and when you're finally confident that she's empty, you fold up the mask and put it back inside her blouse pocket.

A little gift for later, from you to her.