If you are familiar with the term mangina, it is not exactly that. A mangina and an SLR are both males who play female characters in online video games, but an SLR is an extreme version.
SLR's basically pretend to be females, but that they are lesbians. An easy excuse for talking like a guy, or having cyber with other SLR's that they truly believe to be girls. These men are usually 30-40 years old, balding and not going anywhere in life. Period.
Soem_guy: The 2 fat guys pretending to be pretty lesbians? Yeah how could you miss 'em?
Typically applied to males who play females in online games and try to hook it up with other females (probably played by another SLR)