As stated medicate for sure, no alcohol as it makes bleeding worse . I have several tattoos non on ribs but a friend who is nearly covered entirely swears the tattoo gun skipping off ribs into the space between ribs has got to be the worst pain he has received from a tattoo. The guys got a tattoo on one of his armpits so id take his word for it. I have one on my shin and trust me the sensation you get when the needles hitting bone is one that will stay with you for a lifetime. GL man if i were you i would take some painkillers and or muscle relaxers to mello you out and to generally dissociate when your getting tattooed. I find if you keep your mind occupied the pain is really not bad at all, sitting there just focusing on whats going on with the gun and how bad it hurts is def not the way to do it .