I had a rather difficult one in a restaurant the other day because we (my wife and I) were seeing my parents. They always bring out the worst in me, especially my mother because she believes the worst of every situation (it's where I get my glorious anxious mind from).
Literally a minute after sitting down everything started. My legs got heavy and I began imagining that I couldn't walk out the door. My heart was pounding, my head was swimming with thoughts, my gut was churning away, everything was wild for several minutes. I somehow managed to order food (not sure what I ordered but it was tasty) and made it through, but every single moment was an excruciating siege of something else followed by something else. In the span of about 45 minutes, I gave myself every ailment known to man and the pounding in my chest would not stop until I reached the parking lot and realized it was over.
I'm not on any medication and I don't really have an "out" other than going through it, but the relief after it being over is honestly better than anything.