Mockolate is a product introduced in "The One With The List". While Monica is looking for work, she finds a job creating Mockolate products. Mockolate is a "completely synthetic chocolate substitute" as Mr. Rastatter, an executive employee explains. They also claim that Mockolate is "even better than chocolate".
In reality, Mockolate is a horrible, potentially dangerous type of food. Monica pretends to love it, needing the money, and tells Mr. Rastatter that she "loves the way that it crumbles" in a completely unique way from chocolate. When he asks her if she is going to swallow it, she tells him that she is "just waiting for it to stop bubbling
Mockolate was denied their FDA approval, "something about laboratory rats". Their company was shut down, but Monica was still paid for her work. Mr. Rastatter cautiously asked Monica if she ate a lot of the Mockolate and if it burned when she peed.
The Mockolate holiday
Mockolate acted almost as a competitor to chocolate. They came to the conclusion that Thanksgiving is not a "food-preparation holiday" dominated by chocolate and that "given the right marketing, we can make Thanksgiving the Mockolate holiday."
Monica prepared dishes such as pumpkin pie with a Mockolate cookie crumb crust, Mockolate cranberry cake, and Mockolate chip cookies, "just like the Indians served". They were not well received by her friends. Rachel told her she couldn't "believe [she] let [her] put it in [her] mouth" and Phoebe said that it is "what evil must taste like."
In her final recipes, Monica used hardly any Mockolate at all.
Monica returned to Mr. Rastatter and the company once again when they created a new product: Fish-tachios. They supposedly "taste exactly like pistachios, but are made primarily of reconstituted fish bits." Before trying one, Mr. Rastatter asks Monica if she's allergic to anything. She responds "cat hair". He apologizes and puts the Fish-tachios away.