A Bowlar Eclipse refers to a bowl loaded, in a bong or similar smoking paraphernalia, so fat that you can no longer see the black resin in the bowl. In a sense, you would be overflowing the bowl, but not excessively.
Yo man, Johnny just loaded such a fatty Bowlar Eclipse. Way better than Ryan's Event Horizon he loaded earlier today.
von Goober of B-Hampster 3. November 2009