S.I.N. is a bit of graffito that gets scrawled around Neponset Circle and Pope's Hill. Graffiti in this vein usually reads "KEEP OUT," or marks gang turf. Not in this part of Boston though. This is friendly terrain that welcomes visitors. S.I.N. stands for "Stay In Neponset." It's like a welcome mat laid out for all to step on. At big neighborhood gatherings the master-of-ceremonies will offer a traditional toast to everyone gathered, "Let's SIN and enjoy it!" People nudge each other and wink and guffaw.
Some people take the acronym more seriously and actually do sin. Nothing mortal; all the sins committed in Neponset are the venial kind: wedgies, whoopie cushions, white lies...it's a community of cut-ups made up of the nicest people you'll ever meet.