11/29/2013 08:13 am ET Updated Jan 29, 2014

Laughter Is the Best Medicine

They say that laughter is the best medicine.

I don't know anybody that doesn't love laughing until their sides hurt. But why is it that we all seem to have a different sense of humor? And is it just me, or is what people find funny these days changing all the time?

It wasn't too long ago that when we heard the word "funny," the first thing that came to mind was a knock-knock joke or a riddle.

I don't even know how to describe people's sense of humor today, but I can tell you one thing: it sure isn't that simple. Take a look at some of the viral YouTube videos from the past few years and you'll see what I mean:

1. Llamas With Hats

Why does a cartoon about llamas that wear hats and eat people's hands have over 30 million YouTube views?

2. "Friday" by Rebecca Black

Okay, we get it: Rebecca Black loves Fridays and is looking forward to the weekend. Is it really funny enough to still have people running around singing it every Friday to this day, years after it was originally uploaded? Over 60 million viewers think so!

3. "The Fox (What Does the Fox Say?)" by Ylvis

Over 250 million people (and counting) logged onto YouTube to find out what the fox says -- and that's just since the beginning of September!

And don't even get me started with HowToBasic. I'm sure you've at least heard of it, considering it is a YouTube channel with well over two million subscribers. This might actually be the strangest example of our sense of humor today yet. Honestly, why do we find it so funny how they violently smash eggs into their homemade "Dr. Pepper"?

Don't get me wrong -- I completely agree that every one of these videosis absolutely hilarious. I just think its so fascinating how what we as people find funny changes as the years go by. And it's not just YouTube videos: it's memes, hashtags, vines, everything.

How do you define "funny"?