What they don't see leave, they won't miss — at least not yet.
When you perform sleight of hand on an unwary mark, you succeed and no one's the wiser. If you're being watched, roll+DEX: on a 10+, you succeed and no one's the wiser; on a 7-9, you succeed or no one's the wiser (your choice).
This work includes material from Stonetop by Jeremy Strandberg, published by Lampblack & Brimstone, licensed under the Creative Commons Attribution-ShareAlike 4.0 International License.