He may have meant "skulling" and just fat-fingered the "k" instead of hitting the "l". Were that the case, a more proper term would have been "crew", which is the sport of rowing a "skull" on flatwater. You may be familiar with this sport. The uninitiated may call it "rowing". The sport of crew can also be performed in a skull built for a single occupant.
See images below:
But being that the OP is lance, maybe he really did mean skulking...