The two ex-employees claim -- in lurid detail -- David's office was more like "Animal House." In the suit, one woman says David approached her from behind, picked her up by her legs and held her upside down ... exposing her underwear. She claims she had to scream for help before he put her down. According to the docs, he also tied her to a chair with computer wire once. She claims she was fired for reporting him.

The other plaintiff says David once had her in his office, with the door closed, and approached her from behind. In the suit, she says he "rubbed his crotch against her rear end and rubbed his right hand on her dress directly over her vaginal area." She claims she was fired for rebuffing him.

TMZ broke the story ... David is also being sued by a male ex-employee who claims the boss man showed his homemade porn around the office. In their lawsuit, the women also accused him of making employees watch porn, like the infamous "2 Girls, 1 Cup."

And according to the docs, filed by celebrity attorney Lisa Bloom ... David's HR department was a total joke to workers because it had a sign on the door reading "Her-ASS" -- followed by "We Will Give You Just the Tip," and a picture of a man grabbing a woman's breasts.

The women -- whose names are btw, Chastity Jones and Elizabeth Taylor (no relation) -- are suing for lost wages and damages.

Alki's attorney tells TMZ ... the allegations are completely false, and the women are targeting him to pressure him into resolving a previous lawsuit he has against them.