LAG play is playing the hands the TAGs fold.

making loose calls with a draw without pot odds (but implied odds are there)

when you see someone in EP raises 4 to 6x the BB and they get one caller.. original better raises the flop with double the pot sized bet, the player calls, another rag hits, the AA hand pushes all in, again the caller calls, flips over this 74o for the straight and destacks the tighty.

thats lag play.