I know what you all mean! My dd is 10 now + doesn't need to be constantly entertained, but her 6 year old brother does!
If I have a friend round for coffee, even though he's got her child/children to play with, he'll use that time to come up with every single request he can think of!
A toy will need new batteries, he's making something + can't find the sticky tape, he'll bring down a new boxed toy not yet opened, (which of course needs a screwdriver to put together), or he'll suddenly demand a certain remote control car that I know hasn't been played with for a year, + expect me to know exactly where it is. If I don't respond to these requests, cue tantrums in front of whoever we've got round!
He is autistic, not that I use that as an excuse, but after years of letting him constantly interrupt I'm trying to be firmer now. I think he's finally realising that I expect to be able to chat to friends relatively uninterrupted! People used to comment, "Oh you're so patient with him!", but what they prob meant was soft!
He's a lovely little boy btw, (as long as my attention is solely focussed on him)!