A bunch of stuff I doubt we'll ever see in the Buffyverse: these guys acting their ages, starting with:

...Spike creating a stink at Denny's because he tried to save a buck by presenting his AARP card at the cash register after feeding his mortal henchmen and the management won't believe him.
...Angel getting huffy because the local Senior Citizen's Center refused him membership because "Who's he trying to kid?"
...Dru pitching a hissy fit because she doesn't get a Sr. Citizen's discount at the local Wal-Mart and they're having a clearance sale on five pound cans of glitter and cattle prods.
...some hot July evening in Sunnydale, around nine: the Master in a grubby wifebeater, plaid Bermuda shorts and black shoes with white knee socks, sitting in a rocking lawn chair in the outer doorway of his crypt, swatting flies with a rolled up newspaper, drinking blood out of a Mason jar, and yelling at the younger vampires to "Get off my property you damned kids!"
...Dru attacking her latest meal while wearing house slippers, a pink terrycloth bathrobe and rollers in her freshly blued hair.
...Dru dozing off in the middle of the above meal, causing the younger vampires to holler at her until she wakes up and finishes the job.
...any of these guys getting nasty because they get thrown off of the bus and have to pay full fare because they're obviously too young for the senior discount.
...the Master arguing with a sales clerk because back in 1340 he remembered that whatever it is he's trying to buy was only 2ยข and not $30. "And pull up your pants young man. You look like an idiot!"
...Spike getting ugly over not being allowed to collect Social Security because he doesn't have a social security number as he never bothered to register. Had he bothered, I doubt that the Social Security people would accept a death certificate from Great Britain as adequate identification. And never mind that he's never held a real job in his entire undead life!
...how about the look on Spike's face when Immigration shows up armed with holy water and crosses and chuck his and Dru's pasty demonic asses out of the country as unregistered illegal aliens thanks to the fuss he caused over at the Social Security office?
...followed by Spike getting even uglier because now thanks to his and Dru's little brush with U.S. Immigration, Inland Revenue, the British answer to the IRS now knows about him and has slapped a huge tax bill on him because he hasn't paid taxes for the last one hundred and twenty five years. Never mind that he's been legally dead for over a century, Inland Revenue doesn't care!
...Dru forgetting to get dressed before she goes out for the night's dinner and dancing.
...wait a minute, Dru probably does that anyway, sorry for wasting your time!
...The Master's minions rioting just after he announces that he really isn't into World Domination after all. He'd rather wear white patent leather shoes with a matching belt, plaid pants pulled up to his armpits, a visor, and a pink polyester golf shirt while playing Bingo over at the local Catholic church in between day trips to the nearest Native American owned casino with his new girlfriend Mildred who chain smokes Virginia Slims and carries an elderly poodle in her huge handbag. "Kids these days! Close the damn crypt door, you're letting all the air conditioning out!"
...Spike's horror the night he realizes that what he really wants to wear isn't black leather, but running shoes with black socks, pastel blue doubleknit polyester high-water slacks pulled up to his armpits, a Hawaiian shirt, suspenders and a golf cap with a "I'm a sexy senior citizen" silkscreened on it.
...catching "The Anointed" dancing to a Barney sing-along video while picking his nose when he was supposed to be plotting the Apocolypse.
...Dru throwing a tantrum because the warranty on her taser just ran out. "Whiiiiiiiinnnnnnneeeeeeeee! No more after dinner fireworks, no more pretty sparkles, I want my money back!"

And for Angel fans:

...Angel getting nasty because he allowed some telemarketer to sell him aluminum siding for the Hyperion and the workmen never showed up even though he'd paid in advance. Just like the guy who was supposed to resurface the driveway with miracle tar, or the guy who was going to put in the space-age storm windows. Never mind that only yesterday he gave somebody who sent him an e-mail the number to his bank account and his safe deposit box so that they could get their money out of Nigeria. Lucky for Angel and his un-life savings, the Nigerians turned their noses up at the $3 in counterfeit bus tokens, the dry cleaning ticket from 1929 for a suit that he keeps forgetting to pick up, as well as that big ball of string he's been accumulating since 1850!