A blue dot is a sex offender, often a
child molester. The term comes from the way the majority of
neighborhood safety websites display sex offenders
in your area (active residence = blue dot).
Leo: Yo, fuck is this blue dot shit anyway? Niggas won't
shut the fuck up about them fuckin' colors and it's gettin' me mad tight, B.
Omar: Bro, you do not want to go there; that blue dot
on the map? That's old-man Mackenzie's house—he's the pedophile of Fall River. I heard he did some gay shit with
one of those big-ass dog dildos.