Because your mommy friends:
Are willing to do mind-numbing things like go to a Gymboree class with you to beat out the rhythm of the "The Wheels on the bus" on an African drum at 9 a.m. on a Saturday.
Know better than to call you at 5:30 p.m. to see if you want free tickets to go to the game at 7 p.m. They know that this may elicit a rage stroke and therefore they need to give you at least 48-hours lead time before making such an offer.
Understand that sometimes you need to cry to them. Just because parenting is hard. Not because your kids make you unhappy.
Are happy to spend an entire night drinking wine and discussing the ins and outs of such newsworthy topics as: how your son's poop has been weird lately, why your daughter feels the need to put Cheerios in the toilet, etc.
Are willing to schedule get-togethers around nap times and not think you are a compete and utter social pariah or that you let your baby rule your life.
Don't question why you always faintly smell like vomit and syrup, though you haven't been out partying.
Are willing to take your child at a moment's notice if you are in need. No questions asked.
Have extra diapers, pacis, onesies, etc. so when you are in a pinch on a playdate, you aren't left high and dry.
Don't feel sorry for you when you are together and your kid pitches an epic fit. Your mommy friends just laugh and say, "I have so been there, but worse."
Let you share your parenting war stories without judging you or thinking you are a bad parent. They usually follow up with their own, that make you feel 10x better.
Will not give you the deer-in-the-headlights look when you talk about your daughter's hand foot and mouth spreading to her butt.
Can give you advice on how to start solids, get your baby to sleep through the night, deal with separation anxiety and hide your flask in the diaper bag at church.
Are always there for you when you need to vent about how annoying your kid is. They are also there to listen to you gush about how awesome they are.
Understand that sometimes wearing yoga pants and a ponytail are as classy as it is going to get for your lunch date.
Understand that having children often requires the consumption of copious amounts of alcohol.