I take it this was before the movies came out…
Yes. This was in 2000, and the first movie was released in 2001.
But I also remember that I was at that job when they were casting for the movie. It was a fairly big deal when Radcliffe, Grint and Watson were chosen, and this particular company was tangentially connected with the film business. So you wouldn’t think such a thing would have gone over my coworkers’ heads, but apparently so.
You definitely should have said something to Ken, his errand took a lot of time away from you and several other people.
I pitted two of my cow-orkers just Thursday or Friday for being noisy, but this OP reminds me of something else regarding Nicole (names changed).
Nicole likes to go to her mother’s house at lunch. (We get an hour for lunch) She will sometimes bring her lunch, or eat lunch at her mother’s, but other days she asks me where I am going and has me pick something up for her. Now…I also generally pick up lunch for Lucy and Tina (who happily do the same for me). I don’t have a problem doing this, except about 2 months ago I noticed she never asks us if she can pick up lunch for us if she goes out to a restaurant to grab something. No, it’s not a big deal taken on its face, but to ask someone to do you favors constantly and then to sneak out to avoid returning the favor occasionally is pretty crappy IMO.
Lucy and Tina seem to have noticed as well, and we no longer discuss who’s picking up lunch where when she’s around.
~J
My co-workers are afraid to ask what I am reading anymore.
I work at a small place. There are only about 50 employees and since we are school bus drivers and assistants there is usually less than 20 people in the shop at one time. But thee are a few really buddy buddy types there… and then there’s me. The openly disaffected employee. Ya know, a little attitude and people avoid you like the plague. So I get all the privacy I want!
As to the OP, I would have embarrassed the hell out of Ken in the store. Probably would have asked his buddy to call HIM a cab so wonder boy could stand there and continue running off at the mouth and the rest of us could get back to work because we’d all like to GO HOME TONIGHT! Yeah, no wonder I never get invited out.
So Ken spends 20 minutes chatting with his friend, a further 10 making his purchase, and follows this with 15 minutes of additional chat? I’m surprised no one, yourself included, politely walked up to Ken and told him that you had to get back to the office. In fact, if you didn’t do this, I’m not sure you’ve got anything to complain about. Why sit there fuming when just a bit of communication may have sent everyone happily on their way?
Ken, buddie, we need to fuckin’ go. Get your shit together and lets go!
-Repeat as necessary
I have said this to co-workers many a times. But then when I’m pissed I’m very outspoken about it. And usually nobody says anything back because I’m totally cool and calm otherwise.
TM (mostly calm untill ya piss me off)
The OP reminded me of this funny story in this week’s Onion.
I always take my lunch out of the office, if for no other reason I need a break from sitting in front of a computer all day (posting on the Dope, of course 
). I usually get lunch while I’m out, perhaps run an errand or two, and then come back and eat while I continue working. I very rarely go out to lunch with any co-workers, as I’m simply not interested - I’m also of the “I work with you all day, and that’s quite enough, thank you” crowd.
I’ve also noticed that I’ve never made any real friends out of any co-workers, ever.
Esprix
When I worked at a big Germany company, we went to lunch together and - thank God - I haven’t had such problems.
When somebody said ‘Let’s go to lunch’, the others usually were ready to go in a minute or two. We had lunch together, walked some yards around the building (that’s nice, when you sit in front of a computer all day long) and went back to work.
Why not organise lunch tomorrow? Take your car.
Then mention as you head off that you need to drop some things into the dry-cleaners. Best take a book, you’ll be wanting something to do while you’re hiding around the back for 1/2 an hour.