A code name used when talking about your boss in public. This protects you from the unlikely event that the person at the next table is the boss' next door neighbour, brother, in-law or tennis partner.
Joe: "I hear Bert's new girlfriend has a bit of a coke habit"
Gary: "I'd like to hang that prick over a river of burning acid and give scissors to the last 5 people he has destroyed".
A person who is, sophisticated, extremely intelligent and exceedingly well-endowed. A person known as Bert is often the most respected or adored member of any group of people. To be called Bert is the utmost sign of respect: it signifies that the person being referred to has the ability to please and impress others on every possible level.
A woman sees a distinguished, attractive man at a party and says, "wow that guy is such a Bert"