The blue waffle is an image of an infected vagina that has blue pus coming out.
Blue Waffle is the nickname/codeword its been given.
Nasty fungus in vagina that resembles a blue waffle.
A 'waffle' is a a slang term for vagina.
A 'blue waffle' is a slang term for a severe vaginal infection.
It's basically a slang term for an extremely nasty or severe vaginal infection/STD on the vagina. The infection could cause lesions on the outside of the vagina, as well as bruising, which causes it to look blue in color.