found this googlin

"I'll probably get laughed off the list for this, but I've actually had great
success repairing scratched CDs with MAYONNAISE. i know it sounds
incredible, but it really worked.

1) Wash the CD, clear it of all oil and dust particles.
2) Wipe it dry then blow away all cloth fibers.
3) Take a dab of mayonnaise and apply it to the scratch. Rub it in deep to
fill the entire crack.
4) Wipe away all excess mayonnaise.
5) Put it aside and let it dry for approximately 24 hours.
6) Afterwards wipe away all bumps of mayonnaise along the crack with a dry
cloth.

I did it with a (personal) CD that had skipped for months, and it has not
skipped once."