lay a finger on

[lay a finger on] {v. phr.} To touch or bother, even a little. -Used in negative, interrogative, and conditional sentences.

Don'tyou dare lay a finger on the vase!

Suppose Billy fakes his brotherwith him; wilt the mean, tough boy down the street dare lay a fingeron him?

If you so much as lay a finger on my boy, I'll call thepolice.

Compare: LAY HANDS ON, PUT ONE'S FINGER ON.