Take it out of the business expense drawer/cash drawer. ha jk
#6 Gonelifting would not go out to get something to eat.
Knock, then go in. But I would also ask the first time I did it if it was OK. Hopefully the person can tell you definitively what to do next time. <Knock-knock.. "Hi, I didn't know if it was OK to just open the door or not". Then whatever his/her reply was, should be good.
or just ask a trusted person in the office about the knocking thing. Also ask them about the lunch buying thing.
When I worked in construction (yes I did!) We always had one guy go out and get lunch. Every single day he would get stiffed by someone. wtf? It bothered me almost as much as it bothered him. I always had my money out and ready to give to him as soon as he came in the door from buying lunch. Others would "wait till they finished..." then they're forget. blah blah. WTF?
Just pay the man as he enters, period! ARGGGG!.
This is how I would do it. It's a win-win situation. If you go again and he asks you again, just 'add' the two trips together and tell him that. "$4 for Monday, and $6 today... $10." Then he'll see the light. If he doesn't ask again, then it was a one time thing, and the $4 price was not too much to pay for a one time thing.
I wouldn't really ask if I could pick something up for anyone. Just like I don't ask "How are you?" if I don't want an answer.
I know he asked you. That's messed up. But who knows, he might surprise you.