Yo dropped your smile

So there's a vacant storefront in-between a sushi place and a Starbucks on my block. It's prime real estate, yet it's still empty. The windows are completely blank, except for stickers that say the following two phrases:

"You dropped your smile."
...and then, below...
"Smile, you will look younger!"
I'm not sure who put them there, but I find it hilarious. Every time I walk by, I end up - well, smiling. However, the "u" in "you" has rubbed off, so it looks like, "Yo dropped your smile!" All you'd need is that one extra comma to completely change the tone of the phrase. "Yo, dropped your smile!" Yes, I'm a nerdy English teacher :). All the self-help books, the new mantras that will change your life, the New Year's Resolutions - and maybe all it really takes to be happy is to be told, "Yo dude, you dropped your smile!" Maybe that'll make you pick it back up again.