Double Left Hook

Someone I know recently returned from a car show in Daytona Beach, FL.  As a souvenir, I was given these two Left Hook energy drink cans from there.  I've never seen that brand here in the Midwest.

The first was a mango tropical can.  I was told this was the better of the two flavors.  Left Hook is distributed by RaceTrac, located in Atlanta, GA.

The other flavor was citrus.  The caffeine content is 77 mg/ 8 oz, and since these are 16 oz cans with two servings each, that's a lot of caffeine.  For reference, a regular Pepsi has 38 mg/ 12 oz.

I wonder if the name comes from the after-effect when the caffeine wears off... like you just took a left hook to the head.