The Ants in the Pants was a Shen Gong Wu. It could unleash an army of ants to irritate the opponents of its user. According to Dojo, this Shen Gong Wu is a blast at things like parties.
The Ants in the Pants was a golden Shen Gong Wu with a bright, yellow ant at the top. It was in the manner of a food tray with a long black stick on the bottom of it. Across the tray was a black stripe with a pattern across it. It styled a somewhat average size black handle.
The Ants in the Pants had the ability to release a large colony of black ants from within the tray. These ants would make any person who was swarmed by them extremely itchy.
After it was first revealed, Dojo explained to the young Dragons-in-Training that while it's great for things like playing pranks on people (and being used at parties), but it's a pretty lame Wu when it comes to battling, so it wouldn't really be that big of a deal if they ultimately ended up losing it. But the Dragons managed to retrieve it with little-to-no effort, almost entirely due to incompetence on Jack's part. It would later be used by Omi to help Jack Spicer fight Wuya. Later on, Kimiko Tohomiko wagered it in a Showdown and unleashed the ants onto the now evil Master Monk Guan.