You want to date my brother?!

Needed background: Last summer I went out with a boy, T, and we didn't hit it off. He had not come prepared to pay for the meal, and I was not impressed. Although he was interested in a second date, I was not. We didn't go on a second date. T soon left to go back to school.

Fast-forward nearly a year to a picking-up-trash activity with my church group. I was working with T's sister, K, and a new boy, C.  I didn't know C, so I tried to get to know him as we picked up trash. K wandered over to where C and I were working, and so I began including her in the conversation, asking her about her life. I asked about her family, then remembered that I knew T, so I asked how he was doing. The conversation went something like this:
K: T's doing great. He came up a few weekends ago and took me out to lunch.
Me (absentmindedly, thinking of when I spent time with my brother): That's good. It's always nice to go out with your brother. (Then, realizing what I had said), I mean, I like to go out with my brother.
K (eagerly): You want to date my brother?! 'Cause I know you went out that one time and that he really liked you.
Me: No! I mean, it was fine to go out with him, but really...
K (interrupting): I could let him know, and I think you're about the nicest person ever and that you two would really go well together!
Me (frantically): No, no! The date was fine, but I really don't want to go out with him again! (then backtracking after seeing the stricken look on her face) I mean T is great, but I'm not really interested in him. What I meant was that it is always fun to go out with one's brother - you liked being with your brother just as I like being with my brother.
Long pause while C watches us intently, having listened to the whole conversation and forming all sorts of judgements about my articulateness under pressure, not to mention my social life.
K (sullenly): I think I misunderstood you.
Me: .....So, how are the rest of your siblings?

I doubt she thinks I'm the nicest person ever anymore. But at least we got any confusion cleared up!