Rude behavior

[binky]

I need any advice you guys could offer about how to stop kids (mine are 11 and 7) from interrupting me when I am talking. I don't mean the excited breaking in kind either. They just start talking like I wasn't even talking first. BTW husband does this sometimes too, which is obviously where they get it from. I got so mad yesterday, I threatened to start just walking up and smacking them on the back of the head, no warning or anything. I would like to handle this in a gentler way than that, of course.