Torben makes a great point, about natural consequences. I agree with Paul Cline about the specific phrasing, but letting the girls experience the natural consequences of their mistake is likely the best medicine for making it stop. Now, since you mention it isn't the first time this has happened, there is some evidence that perhaps the teasing did not do the trick.
When my own daughter tried to cut her hair, I took her into a salon and while the secondary haircut was happening to "fix" the chop job. I asked the stylist to explain how much schooling she had done in order to learn to cut hair in a way that makes it look good.
The stylist spoke about hours of practice, we saw a practice mannequin she happened to have in back and Alice got a pretty good lesson in how perfecting a skill takes time, training and practice.
Removing scissors entirely from her experience is not a good idea because she does need practice using them for fine motor skills development. We had already limited access to the scissors unless she was watched until we thought we could trust her to use safe scissor practices and had only recently let up on the always watching part. We returned to monitored scissor use only after her "experiment in styling" and she learned that trust sometimes has to be re-earned when it has been lost (another good natural consequence).