Spur of the moment kinds of decisions can be fine for many things, but I would personally think very hard about anything that's as permanent as a tattoo (i.e. costs a lot of money to get rid of). Now, I'm the precautious type, so you might see things differently, but here's how I see it:
I don't know what is going to happen in the future, I might change my style completely for example or other things. Having a tattoo is like locking a part of your body into one style, so if I'm ever having a tattoo, I will have thought long and hard about if it's something I will like in the future.
And how much do I want to maintain it? Tattoos can fade if they're not kept, and may need touchups if it does fade, in order to keep looking sharp. Tattoos will also change alongside the body, so if I grow (one way or another) the tattoo will stretch and vice versa as well. And what about when I start aging more, and my skin may get flappier or I get wrinkles?

There's a bunch of things to consider, not to mention potential health hazards from the various colors that are used in tattoos. I don't know a lot about that though, so don't take my word for it.

Its nice but why don't you just get yourself a N7 tattoo