Here's some reasons why someone might be a lesboy or turigirl:

• Men experiencing queer attraction to women, women experiencing queer attraction to men
• People in general experiencing queer attraction to men or women
• Being a lesbian that likes being called a boy, being a gay that likes being called a girl
• He/him lesbians, she/her gays
• Butch lesbians and twink gays are people I often see using the lesboy and turigirl terms (But it's not exclusive to them! Bears, femmes, anything between or outside of that can identify with being a lesboy or turigirl)

And so on ^^