Polinsky made the damning allegations Wednesday at a news conference flanked by Eggert and his attorney, Lisa Bloom. Polinsky claimed Baio sexually harassed him and ultimately assaulted him -- with a cup of hot tea to the face -- between the ages of 11 and 15 years old.
The former child star claimed during his first year on "Charles in Charge," Baio called him a "f****t" after witnessing Eggert on Baio's lap. Polinsky alleged Baio "pulled down my pants in front of over 100 people."
Perhaps, the most bizarre allegation -- Polinksky claims Baio exposed his genitals through a hole he'd cut in Polinsky's private dressing room.
Polinsky says he doesn't intend to sue Baio, but he does want a public apology. Eggert was also at the news conference, and got emotional while talking to reporters.
As we reported ... Baio's team is set to hold its own news conference at 2 PM PT. His rep called Eggert, Polinsky and Bloom "sleaze mongers."