"If all your friends jumped off a bridge would you do it too?"
xkcd.com, comic #1170
http://www.xkcd.com/1170/
Yes. Most of my friends are reasonable, logical folks. So if they are all jumping off a bridge, either:
1. They all went crazy at the exact same time.
2. There is something dangerously wrong with the bridge or something about to be wrong with the bridge. Like a giant boulder, semi-truck crashing, giant floodwater wave, alien laser, velociraptor.
Probability of #1 is far lower than #2, in my estimation.
Anyway, back to the tattoo:
IMHO, most folks should get a tattoo only if they really want to make a permanent statement about something that is close to their heart/soul. And some folks are probably better off never making that decision, due to bad impulses that they think are long-term sensible decisions.
I never had the desire to get a tattoo until my Dad passed away, at which point I considered getting a tattoo of a Welsh dragon on my calf (he was born in Wales). It took me another 10 years or so to actually get the tattoo - at first I wanted to make sure I really wanted it, and then it kind of faded into a "one day" thing, and the idea was eventually re-ignited when my girlfriend (now wife) mentioned she was looking to get another tattoo for a particular significant memory/associate too.
On the other hand, I know lots of folks who have lots of tattoos, and get them almost like they are collecting artwork. And I've seen some really nice art on some really attractive young ladies, and it only added to the mystique. I am curious what they will look like in 30 years, though...
But I do not suggest getting a tattoo just because your friends have one. Wait until you really really want one, almost need it.
But, that's just my opinion. On the other hand, you solicited opinions, so I assume you value the input...