This is your basic game of keep away with a bit more structure. This drill is also commonly used in hockey and soccer. For lacrosse this not only works on the stick skills of the offensive player but also teaches the defense how to slide and recover as well as handle Man Down or unsettled situations.
four players on the perimeter set in a box with three defenseman in the middle.
The offensive player will pass to the open man.
Defensive players should never let a skip pass go through and should instead give the offense the adjacent pass. If a skip pass goes through the defense should do some form of token punishment. ie... 5 push ups. This prevents the defense from cheating and hanging out on the perimeter and is how a defense would have to play in regular Man Down in a lacrosse game -- just as the offense should be looking to find a "skip to score" pass.