if you cross a chemical and a bicycle?

BIKE CARBONATE OF SODA.
Which Elizabethan Sailor could stop bikes?

SIR FRANCIS BRAKES!
Your reaction to those jokes--whether you rolled your eyes or laughed so hard you snarfed -- is because your brain is functioning properly. To continue operating as the incredible human being you are (with so many people that love you dearly), I IMPLORE you to wear a helmet while biking to protect your fragile brains.

stop thinking your hairdo is more imporant than your brain-do.
stop saying, "but I bike carefully" because accidents happen.

and I promise you won't develop an underbite from wearing a helmet. pick a cool one!
WEAR A HELMET. IF FOR NO OTHER REASON THAN BECAUSE I LOVE YOU.