我有一个英语脑筋急转弯不会做，请大家帮帮忙！

There is a pun in it. Cold, as the opposite of heat, also means a kind of illness, as in "catch a cold". Since people can catch a cold, like cold is something people can grasp, cold is not that fast. So heat will move faster, because people don't catch a heat, i.e. heat is uncatchable.

I cannot kown what the NO.2 foller say
My English is so bed~!
Cold??What is meaning?