An aspirin mask is what it sounds like. You crush up some aspirin (not ibuprofen or acetaphetamine!) and mix it with some some hot water. When it cools you apply the mixture to your face for a period of time.
I’ve tried this a few times with mixed results. The first time I crushed up 4 aspirin (325mg) in a half cup of very hot water. When it cooled down a bit I dipped my fingers in the cup to collect little bits of aspirin residue and applied it to my cheeks. After about 5 minutes it began to really sting so I removed it. My face got worse and there were hard lines between the red and white skin around my eyes. However the next day my skin was softer and the base redness may have been slightly decreased.
Take note: you should really do a spot test before trying something like this. Apply the mixture to your wrist to test for reaction.
I have since tried this several more times but instead mix 7 or 8 crushed apirin in a small cup of strong green tea. I’ll then either soak a face cloth in this mixture and put it on my face or use a cotton ball to continually dab my face for 15 minutes or so. I have not had the same stinging or swelling sensation I got during my first attempt.