Bordering on bragadocious
This is a less rude, subtle approach to curb someones bragadocious behaviour during conversation. It limits the chance of copping a smack in the grill from the offending party.
Hey wigga, i know your missus is a pornstar and your best mate is the lead singer of N'Sync but im sorry unfrotunately i think you might be bordering on bragadocious.