Can sour cream and ketchup plug a kitchen sink?

I rinsed the leftover Rubbermaid containers and the kitchen sink is plugged. The maintenance manager just fixed my sink with liquid plumber last week. I am embarrassed to tell him to do it again. I was told that it would cost $50 – $100 for a plumber if he can’t fix it. I see him tomorrow when he removes my A.C. . I was told that only water and soap should go down the drain. I’ve been using paper towels and a grease jar in the freezer for yucky stuff (grease and butter). To keep them out of the plumbing.