1. With lead, as in to blaze a path that others follow: Someone whose horrible taste leads others to believe he or she is cool and starts a trend that will ultimately die a horrible death at the hands of the fashion police. aka, Prince or Lady Gaga
2. With lead, as in a dense heavy material that sinks rapidly:
a. A person who's chronically bad decision making skills make it obvious to all witnesses that he/she is going to completely destroy his/her own life.
b. Used a a simile: Used to describe a person with a prodigious oral fetish.
Example for Definition 1:
Jenny: Don't you love my new outfit! It's so Lady Gaga!
Jill: Wow, that's amazingly horrible! Lady Gaga is a lead lemming, and you're just a tool.
Examples for Definition 2.
a. Larry: Did you hear that Bob sold his house for $300k and said he was going to invest all the money in lottery tickets?
Dave: Wow, didn't he buy that house for $2mil just five years ago? What a lead lemming.
b. Will: Hey, Joe, what do you think of that Jill chick?
Joe: Jill? Wow, I love Jill. That chick goes down like a lead lemming.