The definition of chirk is to cheer up.(verb)
An example of chirk is to tell some funny jokes to a sad friend.
See chirk in Webster's New World College Dictionary
transitive verb, intransitive verb
Origin: ME chirken, to twitter, var. of charken < OE cearcian, to creak, gnash
See chirk in American Heritage Dictionary 4
tr. & intr.v. chirked, chirk·ing, chirks
Origin: Middle English chirken, to chirp, chirrup
Origin: , from Old English cearcian, to chatter
Origin: , alteration of cracian, to resound; see crack.