It's important to remember that symbols, gestures, signs (etc) do not have intrinsic meaning in and of themselves. Humans give them meaning, and the same symbols/signs/gestures can have radically different meanings in different cultures, or even in different contexts.
Here are some examples of what I mean:
We're probably all very familiar with this symbol,
And because of its usage by the Nazis and everything they stood for, and we have an aversion to it--and rightly so. But also there's this,
The swastika has an ancient use and meaning in India, among Hindus and Jains. For them it is a positive symbol, it was hijacked by the Nazis and that's why we have negative connotations about it.
Here's another:
You probably see this upside-down cross and think that it's a satanic symbol. In fact it's not, this is a Christian symbol, it's the cross of St. Peter, and it has been used to represent St. Peter for a very long time because ancient Christian tradition says that Peter was sentenced to be crucified, but he felt himself unworthy to die in the same way as his Lord, so he requested to be crucified upside down.
And here's another:
One might be confused, why would a church have a pentagram? Because the pentagram has become associated with neo-paganism, the occult, and even satanism in our modern culture; but traditionally the five pointed star--the pentagram--was a Christian symbol in the middle ages, the five points of the star represented the five wounds of Christ, and it also kind of looks like it's in the basic shape of a man--Christ's crown of thorns, and the nail wounds in His hands and feet.
Symbols, signs, gestures, etc only have meaning when we give them meaning. Yes, the "horns" hand gesture has been used by some death metal bands to represent the devil, but in Texas it's just "hook-em horns" used by fans of the University of Texas, Austin's football team, their mascot is a longhorn cattle. In popular usage it's just a "rock and roll" gesture, and has no deeper meaning than that.
If you are uncomfortable with it because of one meaning it has in a certain context, then absolutely don't do it. But understand that others can and, very likely, have no idea that it might have a bad meaning in some contexts. It's one of those things that you need to decide on your own based on your own conscience, nobody here is in any position to tell you "it's bad" or "it's good", because it's neither good or bad,
it just is.
The truth is that if one tries hard enough, one can just about find a negative or inappropriate (for a Christian) meaning for pretty much everything. In some cultures the "thumbs up" gesture is deeply, deeply offensive.
-CryptoLutheran