A 'Frosty Johnson' is a mountaineer term to describe the chilling of the male's private area due to the cold temperatures in the mountains.
Ah, getting a bit of a Frosty Johnson up here
When a man is getting some dome, and the female has a slushy currently in her mouth currently.
man a "Why you shivering man, its July?"
Man B "Dude, you know that hot WaWa lady, she just gave me a frosty johnson"
Man A "Sick man, thats better AC!"