how to say the rubber snap/slap back

The natural English phrase is “snap back” for a rubber band or elastic band returning to shape, and “slap back” is usually not the right choice in this context.

Best options

• It snapped back.
• It snapped back at me. if it hit you after being stretched

• The rubber band recoiled. a bit more formal
• The rubber band sprang back. also very natural

When to use each

• Snap back = common for something elastic returning quickly to its original shape.

• Recoil = more formal or technical.
• Spring back = everyday and clear.
• Slap back = usually means hitting back or reacting sharply, not elastic movement.

Example

• “The rubber band snapped back and hit my wrist.”

• “When I let go, it sprang back into place.”

If you want the most natural phrase for casual speech, use snap back.