pepper gas1
/ˈpɛpə ˌɡas/noun
An anti-personnel gas that irritates the throat and nasal passages.
Origin
1960s; earliest use found in Sunday Dominion-Post (Morgantown, West Virginia). From pepper + gas adjective.
pepper-gas2
/ˈpɛpəˌɡas/verb
[with object] To spray or attack with pepper gas.
Origin
1970s; earliest use found in Manitowoc (Wisconsin) Herald Times. From pepper gas.