ants in one's pants, have

1. Be eager for sexual activity, as in Bill's got ants in his pants for Rita . This usage is less common today. [ Slang ; 1920s]

2. Be extremely restless, uneasy, impatient, or anxious, as in This child just can't sit still; she must have ants in her pants . This rhyming idiom calls up a vivid image of what might cause one to be jumpy. [ Slang ; 1920s]