In Steal a Brainrot / SAB , there appears to be 1 Lava Slap listed in the public wiki data I found: Lava Slap , obtainable from the Lava Wheel during the Molten Event with a 0.5% chance.

Quick Scoop

  • Count found: 1 known Lava Slap.
  • Source: the Slap wiki entry specifically lists Lava Slap as a special slap.
  • Availability: it was tied to the Molten Event and the Lava Wheel.

Note

The wording “how many lava slaps exist in SAB” could also mean you want every lava-themed slap variant in the game, but the available public source I found only confirms one by name.

TL;DR: I found 1 Lava Slap in SAB-related public info.