I'm a venereal disease like a menstrual bleed
Through the pencil I leak on the sheet of the tablet in my mind
It may sound like Lil Wayne believes female menstruation is a venereal disease, but that’s probably not what’s going on. He loosely connects the two (they’re both vagina-y and kind of gross to men) to transition into a description of his writing process
Like a menstrual bleed, he leaks blood through a pencil — not onto a sheet of paper, but onto a sheet of a tablet that exists only in his mind. He’s taking a familiar rap trope — “I don’t write my lyrics” — and making it much more vivid