The grown-up bathroom should be a kid-free zone. Otherwise a mom like myself seeking just one fleeting moment of privacy to do her business won't be caught off-guard when she sits down in a puddle of little boy sprinkle and slides unexpectedly to the back of the seat. This toilet seat should be the one place in the house a mom can plant her booty without fear.
Be prepared to spend significant amounts of your budget on kids' shoes. God apparently instilled little men with some sort of mutated Sasquatch gene that leads their feet to grow ONE AND A HALF sizes in just six months' time.
Be prepared to take drastic measures to deal with the crippling mom guilt associated with letting your kids walk around in shoes that are one and a half sizes too small. These methods include but are not limited to: Prozac, counseling, vodka, long jags of crying to your girlfriends over coffee, and/or frivolous purchasing of random toys to make up for the injury to little toes.
Don't fight the inevitable "trickle down" effect of boy habits upon female siblings. My 18-month-old daughter is already walking around peeing on trees and crashing monster trucks.
Lower your standards when it comes to the levels of "appropriateness" on conversational topics about poop, pee, itchy "nuts, privates, or weiners," butt cracks, and burping and farting. Or in the alternative, prepare yourself to fight a really disgusting uphill battle.
Add "What the hell is that smell?" to your everyday mommy vernacular. Trust me, it will come in handy.
Expand your understanding of the laws of physics. A little boy's inertia, velocity, and gravitational potential energy defy the traditional framework which you have up to this point been taught.
Allow embarrassment to wash over you at every opportunity so that eventually, you are virtually immune to the effects of tantrums in department stores, your friends seeing your living room littered with tampons because the boys were sword fighting and/or singing into a teeny, tiny microphones, your son announcing you "pee out your booty" when he is in the bathroom stall with you, and his verbatim repetition to the neighbors of the questionable conversation you and your husband had when you thought little ears were otherwise engaged.
Have a frank (pun intended--you'll see), honest answer ready when your son panics and asks you why his private parts are "tall." In fact, before you reach that point, get over your reluctance to discuss the male anatomy altogether. He will discover it around three months of age and be fascinated with it the rest of his life, so you better get used to it and teach him to be comfortable with his own body. But not too comfortable, mind you. You don't want a seven-year-old who watches TV like Al Bundy or unabashedly "adjusts" himself in front of random strangers.
Give and receive love from your little boys freely and abundantly. The bond between mother and son is special and should be nurtured and appreciated. It should also grow and change as your son grows and changes. Remember, no one wants to have their kid referred to as a "titty baby" when he is in the horrific throes of puberty. And we women of course do not wish to be referred to as a "monster-in-law" one day when our sons are married because we had difficulty recognizing boundaries and cutting the apron strings when the time was right.
Clean a boys' bathroom at least every two days. The whole once a week thing won't cut it--unless you plan on sharing your findings with highly specialized scientists seeking to discover new species of bacteria.