Simple past tense and past participle of teargas. (verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "teargassed" in a sentence
"Major points out teabagger mob about to get teargassed while rioting to disgraced former politician Newt Gangritch."
"After the ouster of President Hosni Mubarak, the population's widespread fear of the police has given way to a general disdain for the forces that beat and teargassed demonstrators during recent protests."
"Here is a video of a man in Cairo apparently struggling with muscle spasms after being teargassed yesterday."