A dirty kitchen counter but more specifically a dirty cutting board....
It could be anything such as tons of crumbs from cutting a crusty bread, dirty cutlery that has been used and left on the cutting board with food still on it, empty or half full cups placed on top of the cutting board, food spills or drips such as jam or honey etc. or just food in general such as pickles, cheese etc.
Whenever I have friends come over this always happens...It's quite annoying.