A
Leary biscuit is a snack consisting of a cracker, cheese, and a
marijuana bud. It is heated in a
microwave oven to activate the
tetrahydrocannabinol (the active ingredient in
cannabis) and cause a cannabis "high" in the eater.
Timothy Leary was reportedly fond of these concoctions, even in the later years of his life, and thus they are named for him.
See also: Alice B. Toklas brownie