'To have ants in your pants' means to be extremely restless, uneasy, impatient or anxious. It is a ryming idiom that originates from the 1920s and brings to mind a vivid image of what might make a person jumpy. 'This child just can't sit still. She must have ants in her pants!'

You've got ants in your pants = you are fidgety; you can't keep still