It says in Gordon Freeman's page that Splinter Cell references Gordon and his crowbar. It says...
"In Splinter Cell Chaos Theory, Anna Grimsdóttír remarks to protagonist Sam Fisher that 'crowbars are for geeky video-game characters', poking fun at the fact that Gordon Freeman is a scientist by profession."
When and where does this happen? I've played through several times and not heard this line.
It is during the level in the North Korean Missile Battery (level 7). When you see the battery you have to investigate, if you try to directly touch it, Anna will tell you you first have to open it. Then Sam will say he forgot his crowbar. And then comes the joke.