Well its the fact that the worm is so concentrated with tequila that it is essentially a super shot. Even without the worm tequila gets the job done!
"Ta-kill-ya", and that's what it does
I recommend a Hurricane. The original Hurricane is New Orleans style and doesn't have tequila, but there are many versions of the Hurricane. Best version includes rum, gin, vodka, tequila, blue liqueur, and brandy. lol...Oh yeah!