old-fashioned; humorous
to not be able to keep still because you are very excited or worried about something: quá phấn khích, quá lo lắng đến mức như kiến chui vào quần nên đứng ngồi cũng không yên.
to be very restless or impatient: rất mất kiên nhẫn
to be so excited, nervous and anxious about something that it's hard to be still and calm.
Examples:
Before, there would be no way I would sit down and take it easy. It was like I had ants in my paints.
My children have ants in their pants because is Christmas and they are excited about their presents.
Every time we take our children to holidays they jump around like they've got ants in their pants and I constantly have to ask them to sit down.