In one scene the girl seems to have no underwear, and they put a mango in front of her crotch because showing genitals is illegal in Japanese media.
The Japanese slang for vagina is manko, which can be written with the same characters as マンゴ but for the extra dakuten (the " on the コ ).
In any case, they’re definitely a pun, in terms of sound.
"Eat my heat" is an anglicism of Japanese slang for fellatio, wherein たべる (taberu, to eat) is often the euphemism.