To be nervous or anxious or jumpy; to be unable to sit still.

If you had 'ants' (small insects) in your 'pants' (clothing) you would probably feel like jumping around.

Synonym: antsy
1) The children had ants in their pants, so we took them outside for some exercise.

2) Would you please stop tapping your foot?! You must have ants in your pants!
by VAKI5 May 10, 2005