Also known as a "BLUNT." This slang term originated in Pittsburgh, Pennsylvania. The habitual pot smokers in Pittsburgh are known for being stubborn and almost ALWAYS smoking their weed out of a blunt. (A blunt is a hollowed out cigar filled with marijuana.) They began using the term "L" because of the resemblence of the blunt and a lower-case L in the alphabet.
"Who wants to twist up this L ?"