I've come up with plenty of stuff off the cuff like the GP writes, sometimes it works, plenty of times it doesn't. I only brag about the times it worked ;)
Basically all groups have their lore. Everyone knows it contains an element of bragging, a lot of BS and some downright fabrication. It's not about fact reporting, its about bonding, it's about highlighting certain aspects to demonstrate traits valued in the group, it's about passing on a generalized knowledge. Hell, some places "shooting the shit" is called "telling lies with the boys".