Frostys or Frosties?

What's the plural of a Frosty?  For some reason, it seems to me like it should be Frostys, but I am sure that isn't right.  Right?

I looked it up on the Wendy's site, and they seem to just avoid the issue by using the singular, even when it deserves to be plural.  Example:  "Hang it on your key ring and for just $1 you can have a free Jr. Frosty for one year at participating Wendy’s."


Regardless, what I wanted to discuss was the "it" of that sentence.  For a $1 donation to the Dave Thomas Foundation for Adoption, you can get free Frostys/Frosties (with purchase) from now until the end of October.  These are the super mini sizes which means that they come guilt-free and are just big enough to satisfy a summer craving.  Pair them with something from the 99 cent value meal and that is a steal of a deal.  And, you don't really  have to hang it on  your keychain.  Mine lives with a lot of other "loyalty" type cards in the ashtrayish thing in my car.