I am the oldest of five. It never seemed like we had lots of kids around the house.
When I babysit five other kids for a couple of days, five seemed like 7 or 8. Two of those five kids were two-year-old twins. WHOA! Need I say more? If you have taken care of two-year-old twins, I don't need to describe the experience; you know what it is like. If you have never taken care of two-year-old twins, I just can't describe it well enough to give you an accurate idea. So, go offer to babysit twins. Their mom will be grateful.
Honestly though, the kids were pretty good (most of the time). The older kids were angels and lots of fun.