Getting a tattoo is one of the best experiences if you ask me, but getting one with your best friend is out of this world. It doesn't have to match, it doesn't even have to be in the same spot, you just have to do it together.
No matter how many tattoos you have there's still a little bit of jitters when you hear the gun start, and having you're best friend feeling that at the exact same time as you makes it so much easier to get through. You're both going through all the emotions together, which is better than any other bonding activity you guys have done. You both have a new beautiful piece of art on you and you weren't in it alone.
You don't have to get matching tattoos for it to be a bonding experience, it's okay if you both have different tastes and can't agree on one. Just knowing that you're best friend is experiencing every emotion that you are is enough to bond you.
Every tattoo has a story behind it, and now you can think about your best friend every time you see it and you can brag about them and their tattoo when you talk about yours. Even if you two drift away and aren't as close anymore you'll always have that great memory about them with you. When you're kids or significant other in the future ask about it you can reminisce on the good times you had with them.
Getting a tattoo is a serious decision and shouldn't be made lightly, but if you are lucky enough to have a best friend who is also interested in getting a tattoo take the opportunity to get it with them. And if you guys do choose to get matching tattoos that's even better. You'll always carry a piece of them around with you and there's nothing better than that.