They have their own bees knees.
Interactive Joke of the Day Mug
Coffee Mug
Deez nuts)
An aero-drone !
Two bees. What's worse that two bees? Three bees. What's worse than three bees? The holocaust. What's worse than the holocaust? Four bees.
The knee. It's a load-bearing joint.
Their knees. (Not sure if this one translates well to english)
To even out the good things that happen to bad people.
Never having to buy another electric toothbrush.