ow...that burns!
I'd have to say that in all of my (limited) experience of doing tequila shots, rarely has it caused me any pain. Sometimes there is a short-lived warm sensation in my throat, but that's about it. Last night, I had some tequila shots with friends. The first round was problem free. Somehow, in midst of my second shot, somebody made me laugh and the tequila managed to come out my nose. My nose and throat began to burn something awful and my eyes were tearing uncontrollably. The burning didn't dissipate right away either. I contemplated snorting some water through my nose in an attempt to get rid of the pain but then decided against it. (I opted instead for the more socially acceptable option of drinking the water.) Eventually, the burning lessened and by the end of the night it was gone completely. But I will certainly be more careful in the future to avoid any such incidents.