This totally happened this weekend to someone I know. Let's call her "Susie". (Not Suze; Susie!)
This weekend "Susie's" husband had a weekend free and they weren't traveling anywhere, so they had a cleaning day. After a good house cleaning, "Susie" thought it would be nice to give herself a little homemade spa treatment. This included a nice bubble bath, a pedicure, and at the last minute, a deep conditioning hair treatment. She called out to wonderful hubby, "Could you bring me a half-cup of mayo?" as she was already in the tub. (Because she's always reading in magazines that you can do all these sort of homemade hair treatments, and also she was inspired by this post...)
Wonderful hubby said, "Okay, but are you sure?"
He was right to be hesitant.
"Susie" washed her hair, then gooped on the mayo. She let it sit in her hair until she was done with her bath, like 20 minutes, and then she rinsed it.
Unfortunately, her hair was kind of tangly, so she of course put in leave-in conditioner to help comb it out. And since she was going on a date night with her wonderful hubby, she put in some of that shine stuff that helps with frizz. And then furthermore, she put in mousse, because "Susie" has very fine hair and needs all the body she can get.
Let's just say that what resulted was better suited for a grease monkey. Or someone who may or may not wash her hair regularly.
And since there was so much product in "Susie's" hair all that was left to do was put it into a pony tail, which she thought would look better on the side of her head. So, yeah, "Susie" went to church with a side pony of greasy hair. For the date she just put it back to a regular pony.
It was like the bad hair day to beat all bad hair days.
I am happy to report, however that "Susie's" hair has recovered and now it looks very nice and not dry.
If you were to try this I would advise putting the mayo in and then washing it with shampoo. Or, just stick with baking soda. That seems to work a lot better.