Prep the glasses: Dip the rims of 4 shot glasses into a bit of water or lime juice, then press them into the graham cracker crumbs to coat the rim.
Shake: Fill a cocktail shaker with ice. Add the vanilla vodka, chilled RumChata, and key lime juice.
Strain: Shake vigorously for about 10–15 seconds until completely chilled. Strain evenly into your prepared shot glasses.
Garnish: Top each shot with a dollop of whipped cream and a tiny key lime wedge. Serve immediately.