Who would have thought that the first use of a Pogues song would be in a commercial about a hockey mom praising her Subaru minivan?
Another one, and even more unexpected than my previous 3: Northern Downpour by Panic at the Disco. Now most of their stuff off of that album would also work as background music, but I don’t expect station programmers to realize it. (Of course, some background music programmers want peppy music, but they would realize that most of the songs on that album aren’t fast rock, so I wouldn’t expect to hear most stuff from that album in either sort of situation.)
Inb4 “Lust For Life” hawking cruises.
I walked into a Walgreens earlier this year, and they were playing “I Want a New Drug.”
Barbra Streisand trying much too hard to wring whimsy out of “Jingle Bells” once sent me running from a grocery store, the cart abandoned in the aisle.
Thanksgiving Day fell on my mom’s birthday last year (she died in Feb 2011). We’d spent the day painting at our new house because I wanted to ignore the day completely.
Went out to eat that night and this started playing.
One of her favorite songs from an obscure album. I hadn’t heard it in about 25 years. At the time I was pissed and devastated by it. Now I wonder if it was her way of saying hi.
Funnier story: my dad’s wake, the Muzak version of “Take My Breath Away” started playing. 
Win.
“It’s a Small World” playing at a local pachinko parlor.
The last few times I’ve been to one of the local grocery stores it’s like a retro 80s dance party. I’ve heard:
“Pulling Mussels (From The Shell)”-Squeeze
“Every Little Counts”- Depeche Mode
“Love Vigilantes”-New Order
“Falling Down The Mountain”-INXS
I also heard “Fresh Feeling” by Eels at Bath and Body Works once.
I can’t remember where I heard it, but it was in the local mall. They were playing Celine Dion singing Feliz Navidad. 
I stood it out, but her verison is about eight minutes long.
G. G. Allin’s I Wanna Fuck The Shit Out Of You in a steakhouse. I wonder what college kid was running the audio system?
Oh, thats right. It was me.
I was at a deceased relative’s viewing a couple years ago when the funeral parlor Muzak played “Sexual Healing.”
Ah, youth. I once played Pachelbel’s Canon at 45 from a 33rpm record on my campus radio station.
My first thought was how long did it take for you to run screaming into the night?
One time I was in the gas station convenience store and there was some benign adult contemporary song playing with a female singing… But it was registering as vaguely familiar. After a few lines I realized it was a cover of I remember you by Skid Row
I was eating an a chain TexMex place…On The Border, I think.
They were playing a string of what I guess they thought were pretty good authentic songs for a Mexican place.
Than a Miami Sound Machine song came on.
'Cuz hey, they’re all Mexican, right?
My gym was playing 'nth degree’by Morningwood the other day. It pretty much made my day.
A couple years ago I was in WalMart and they played… Bobby Sherman’s ‘Julie Do You Love Me?’. I guess the last time I had heard that was about 1967.
What freaked me out was that I remembered it.
At a rural town show (the crowd was all all farmers and Country Women’s Association members) a busker was doing a slow, acoustic version of Sympathy for the Devil - she was pretty good too.
In the waiting room when I was about to go in for my vasectomy, *Ghostbusters *was playing.
That’s funny, because it’s the one Zappa tune I can think of that seems to have been a nice little tribute to muzak in the first place.