Katy Perry has certainly left a memorable impression on this season's slate of contestants.The songstress and judge picked up the mic on Monday's new episode to belt out an impromptu rendition of her hit single «Teenage Dream,» and ended up teaching the young up-and-coming singers a lesson in keeping your composure.Right as Perry hit the lyric, «Put your hands on me and my skintight jeans,» the singer's own skintight coral red pleather pants split in the rear and she bent over.Instead of running off stage in embarrassment, Perry simply asked of the production crew, «Can I get some tape? Some gaffer tape?»ima get ur heart racing in my skin-tight jeans on #americanidol tonight