"I'm afraid"

I say it all the time at work. "Sorry, I'm afraid we're out of skimmed milk." "I'm afraid there's no more carrot cake left." "I'm afraid we're closed now, sorry."
Why am I saying this? I'm not afraid, quite clearly I'm not. It's a bit flippant to use an expression which is about a strong emotion that I obviously don't feel. Where has it come from? When people first started saying it, were they afraid? And if they were, it's surely not a good idea to give it away to people so easily. If you were being confronted by a big burly tattoo-covered man, who was annoyed because you'd looked at his girlfriend, and you told him "I'm afraid I don't want to have a fight with you," then you've given the game away. You're scared, he's in charge, he's going to beat you to a pulp. Sometimes, it's best to play your cards a little closer to your chest.

I scoured Google for an explanation of why we use the word 'afraid' when we're not, so as to present a well informed discussion, but I couldn't find anything.

"Do you know what I mean?"
I say this a lot too. I'm not sure why as I can see all the things wrong with it. Let's say a neuro-physicist is explaining the intricacies of... wait a minute, what do they work with? Physics? Yeh, ok so they're explaining something complicated about physics to me and they say "Do you know what I mean?" There's a strong chance I need them to check as I probably don't know what they mean. If, however, someone says to me, "I just had an argument with my boyfriend. I'm really annoyed now. He's so unreasonable, do you know what I mean?"
Hm. Let me think. Do I know what you mean? I'm not sure, it sounds like a complex situation for me to understand... Your boyfriend?.. An argument?... He's unreasonable?... No, sorry, run that by me again because I don't think I know what you mean.
When I think about how I use it, I always attach it to the simplest of sentences, ones that it's impossible the other person doesn't 'know what I mean' unless they actually don't speak the same language as me.
"It was hectic in work today," I say to a friend, "Every time we thought it was quietening down, twenty more people came in. It was just constant, do you know I mean?"
Ridiculous.

"Can I get..."
I'm in work. A customer comes in. "Can I help you?" I ask. "Yeh, can I just get a latte please?"
Stop here! Can YOU get a latte? No, you can't actually. You can ask me for one and I'll make it for you but it's not self-service. The kitchen can't take more than two people at a time, you can't just go parading in there and helping yourself to all the sandwich ingredients and coffee. Besides, it's my job to make it. I'd be out of work if that's how you bought coffee.
"Can I get?" No!

In other news, Danda would like to say in his defence that the word 'can't' defeats my theory on elongating vowels unnecessarily (14th March post : In conversation with Danda). I say that that's different because of the 'n' after the 'a'. So there.