Bring food. Preferably ready to eat, or at worst super easy to prepare (microwave, removing a lid, possibly putting on a plate)
And your washing up skills
You WILL take the baby. Staying longer than an hour? See you later, we’re going to sleep. Not staying long? Hold him whilst we wee, stretch, clean off sick from ourselves and recoil from him for a bit.
The ability to do household chores. Please hoover my house
Low expectations for coherent conversation
Rose tinted glasses. Yes, he’s spotty and looks like Doug Stamper from House of a Cards, but you tell my wife he is gorgeous or you’re coming off the Christmas card list…!
Baby whispering super powers. PLEASE MAKE HIM STOP CRYING!!!!