lark 2 
(lärk)
(lärk)n.
1. A carefree or spirited adventure.
2. A harmless prank.
intr.v. larked, lark·ing, larks
To engage in spirited fun or merry pranks.
[Short for SKYLARK, to frolic, or alteration of dialectal lake, play (from Middle English leik, laik, from Old Norse leikr).]
larker n.
larkish adj.
larky adj.