code/modules/mob/living/emote.dm

YAWN_PROPAGATE_CHANCE_BASE	The base chance for your yawn to propagate to someone else if they're on the same tile as you
YAWN_PROPAGATE_CHANCE_DECAY	The amount the base chance to propagate yawns falls for each tile of distance
/datum/emote/living/cat	Abstract type for emotes that can be run by cats and those with a felinid tongue
/datum/emote/living/moth	Abstract type for emotes that can be run by mothroaches and those with a moth tongue

Define Details

The base chance for your yawn to propagate to someone else if they're on the same tile as you

The amount the base chance to propagate yawns falls for each tile of distance