I first had this a few years ago and it instantly made me think of those bottle cap candies you had as a kid.
Sure enough it is called a bottle cap and it is sweet but delicious.
I make it as a cocktail instead of a shooter it is so tastey.
The bottle cap shooter is a "drop and shoot" drink. A shot glass filled with sugar-rich liqueurs is dropped into a larger glass with a carbonated drink. The sudden influx of sugar excites the soda, making it foam up and shoot up the glass. The key is to drink it as soon as it foams up, enjoying the sensation of the fizzy explosion in your mouth.
What you need:
Put soda and lime juice (1:1 ratio) into beer glass. Fill high enough that the shooter glass will submerge.
Put half Rootbeer Schnapps and Half Raspberry Pucker into shooter. (1/2 oz each or if you are using a 2 oz shot glass 1 oz of each)
Drop the Shooter into the Beer glass and drink. It will foam up, the more soda the more fizz. I often just make it all in one glass as a cocktail because I love the flavour and don't care about the fizz.
Play with the amount of soda versus lime and the size of the glasses until you find a ratio that works for you. I like mine slightly sour so I add a bit more lime juice/sweet & sour mix.
MMMmmm... now tell me that doesn't remind you of being a kid?