Alright, this one time I tp'd to a new player to place water and his pants were glitching out.... which was really funny when he was riding a pig.
Then there was the day that squids thought they were dolphins and were leaping out of water
This one server I play on two players got "married" and someone waited until they were about to kiss before throwing an invisibility potion on the wedding party xD This happened three times before the couple kicked everyone out and moved on xD