What is the meaning of Slammer?

One who, or that which, slams.

Jail, prison.

A tequila cocktail that is slammed onto a surface to induce fizzing.

One who takes part in slam-dance.

One who competes in a poetry slam.

In the game of Pogs, the heavier piece used to strike the stack of counters.

A slam-door train.

A fraudster who carries out slamming (fraudulent changes to a customer's service).

to crowdsurf

to take part in a poetry slam

clatter, clattering

Source: wiktionary.org