Welcome to the POG Wiki
Slammers were a central element of pogs. After deciding the players and stacking the pogs, the active player would throw a heavy metal or plastic disc onto the top of the stack to try and flip as many over as possible. There were named variations on technique and this caused a lot of debate on the playground. Below is a link to a video by Old Toy New Joy explaining the intricacies.
https://www.youtube.com/watch?v=rk1mb37UOYY