Episode: "All Halliwell's Eve"
Air Date: 10/26/00

At the start of "All Halliwell's Eve," the Charmed Ones (save Phoebe) are dressed, quite originally, as witches. When a coven of 1600s-era witches zaps them to the 17th century for help, the sisters' costume lameness proves problematic, because in 1670 no matter how hot Piper looks in the dress, a Glenda the good witch costume is a one-way ticket to a fiery stake.