Bamboo prefix, the bottom is a substitute word, how to read it?

There is a "Dai" at the bottom of the prefix "bamboo", and the word is: mm-hmm.

What is this? "I put my foot in my mouth."

Number of strokes: 1 1

Radical: bamboo

Stroke structure: upper and lower structure

Stroke order: left, horizontal, dot, left, horizontal, dot, left, vertical, horizontal, oblique hook, dot.