Ants in one’s pants
(PW)
impatience for action or activity : restlessness
(UsingEnglish.com)
If someone has ants in their pants, they are agitated or excited about something and can't keep still.
(thePhraseFinder)
: : If I find anything else, I'll post again. But the phrase is quite literal. If a person sits on the ground, like during a picnic, he or she probably will get ants in his/her pants. And that makes a person fidget.
: Here's a slightly different meaning and a possible source. Although I think the phrase is a lot older than the 1930s.
: ANTS IN HIS PANTS - "Excessively restless or eager. Hugh S. Johnson, the colorful former Army general who headed the National Recovery Administration in 1933-34, may have originated this phrase but certainly made it popular. 'Full of beans' and 'full of red ants' convey the same idea." From "Dictionary of Cliches" by James Rogers (Wings Books, Originally New York: Facts on File Publications, 1985).
And here's a later origin date and another different meaning:
"Antsy - Originating in the late 1960s, antsy means jittery, restless, nervous. The expression drives from the earlier phrase 'to have ants in one's pants,' which dates back to World War II America and seems to have first been recorded in humorist H. Allen Smith's book 'Putty Knife' (1943): 'She dilates her nostrils a lot, the way Valentino used to do it in the silent movies to indicate that he had ants in his pants.' The quotation shows that 'to have ants in one's pants' can suggest lust, but to my knowledge 'antsy' never has this sexual meaning." "Encyclopedia of Word and Phrase Origins" by Robert Hendrickson (Facts on File, New York, 1997).
