Not sure what to do, when masturbating, and someone walks in on me?

I do it quite a lot as I really like it, but I've been caught out a few times lately by friends and family. This doesn't really bother me though. But, I'm torn on what to do, for some reason it always seems to be on the vinegar stroke, you know the point of no return, when they walk in on me, and as I'm a perfectionist, I don't like to leave things incomplete. Now, when someone walks in on me, do you think they would mind if I carried on, especially if the motherloads about to fly, or should I stop, It is really hard to stop though when I'm at that point, as it's the best feeling in the world, any help would be great, thanks.