This "Parent's Bill of Rights" (via the Blogfathers daddyblogging site) encapsulates some should-be-truths about the world:
1) Unsolicited parenting advice shall not be offered to parents of small children.
3) No one person, without the express written consent of a child’s parent, shall introduce that child to any or all of the following: Elmo, Barney the Purple Dinosaur or the Teletubbies.
4) All parents shall use their kids as an excuse for not doing something they don’t want to do at least one time per week but not more than five times a week for fear of sounding inept.
6) All parents with children under the age of five shall be free of riducule when caught singing “Wheels on the Bus” while at work.
I like #11, offered in the comments, too:
11) A parent who does not watch their child in a public place (ie playground, etc.) should not be surprised when another parent reprimands said child for picking on the child of the reprimanding parent.