Made an ant be labelled as a liar and felt good about it
I was a little too bored. So I placed a few sugar pieces in front of an ant. She nicely ate a few and went on get her friends.
Before they all returned I hid the sugar. Now they all think she was lying.
Yes I have no life.

I remember seeing this video on Instagram (could be fake) where someone managed to tag a scout ant, and would hide the sugar cube only whenever that specific scout ant would discover it.
Apparently it took 3-4 days of betrayal before the ant colony ignored that scout ant altogether. Just goes to show that betrayal is an effective pesticide.