a Friday funny

I was grading papers this morning (in between browsing through my digital photography wedding book, which I spilled coffee on and broke the binding to and will now have to replace cause it looks yucky).  Amongst the hum drum papers was a glimmer of wowza.
This was the end sentence of a student's essay:

There's a reason they're called cowards.  Ever seen a cow stand up for herself? 

And that's no bull! 

From the same student, in a different writing:

"...everyone thinks I'm like the beans knees..."

Now I know the expression bees knees - which I don't get - but what kind of bean has knees, and why would you want to be a bean?

Sometimes the chuckle makes the tedious nature of grading more of a discovery adventure.