Portmanteau contraction of "Loose-Aggressive/Tight-Aggressive". In poker, someone who plays a style somewhere between tight-aggressive (TAG) and loose-aggressive (LAG), raising and reraising a wider range of hands than might seem wise, but doing so with judgment and care, picking opportunities carefully. Often a LAGTAG player will seem to be playing a wide range of hands indiscriminately, when actually they are playing tightly against strong opponents and loosely against weaker ones. Because of their perceived looseness, a LAGTAG can get more action from a TAG than another TAG would.
The local Vegas rocks and nits didn't have what it take to play against the seeming tourist's LAGTAG style.