When out for a meal with DP last night (only Pizza Express, nothing too fancy!), and we were sat right next to a table for two where two young girls (10ish) were sat at. Their mums were sat on another table within sight in the restaurant, and i'm guessing the girls were allowed a table together as a treat, which is fine.
However, the girls were, in my opinion, behaving totally inapropriately for a restaurant, chucking a napkin around (so it landed on a lady behind them, who had a word), and then getting up and running around, before standing having a tickle fight so they nearly piled into DP and my table.
As a result, I let rip slightly, and told them "can you SIT DOWN PLEASE, THIS IS A RESTAURANT NOT A PLAYGROUND" rather loudly 
. I stand by what I said, but felt like a bit of a grouchy old tit (i'm only 26 
) and DP was mortified by my outburst. Their parents didn't seem to give two shits though.
Possibly pg hormomes (i'm expecting my first), but am I unreasonable to expect parents to make sure their kids behave when out and about? Nothing against children being out in the evening though, as there were loads of well-behaved ones around. What also got me is these kids didn't seem to care that they were being told off and just shrugged and giggled- when I was that age i'd have been mortified to have been told off by another adult!