Something that should be implied in many situations. I don't hate kids, I think they're cute, I hope to have a set someday, but there are some places where two year-olds do not belong, but it seems as of late there are many people who don't understand what should be
common sense. Here are a few places where I have seen babies where babies definately do not belong:
A movie theatre, especially one showing a rated R movie. You have a baby, who is not going to get anything out of this movie, who will cry when the lights go down, will cry when there is a loud sudden noise, will cry just because he/she feels like it, will annoy the fuck out of everyone in the theatre when it chooses to cry and will render you unable to enjoy the movie because of tending to the baby's needs. And when you really think about it, do you need to force a movie such as The Cell on the fragile developing mind of your child? Do you think your offspring is going to get the jokes in Meet the Parents? I didn't think so. I realize that it is difficult to find a sitter on short notice, but for the benefit of all parties, including yourself, just rent a movie that can be paused when your baby needs to be changed, fed, or otherwise attended to.
Live theatre. You paid upwards of $60 to see Riverdance, the least you could do is pay a 15 year old neighbor 10 bucks to watch your kid for the evening. You think the people in the movie theatre got pissed off, just wait until your kid starts screaming in the middle of that soprano's solo.
A math lecture. A distinguished professor from another university is doing a guest lecture and you really want to go, so why not bring your kid? If you scream at your two year old enough, I'm sure that he will be more than happy to sit quietly for an hour and a half. A woman seriously brought her two year old to a lecture at my university. When her kid wouldn't be quiet (which was every three minutes or so), she would drag him out in the hall and you could hear her spanking and yelling at him as the door closed behind her. Then she'd come back in and the process repeated itself throughout the entire lecture. I'm sure the professor was impressed, as was the audience.