you're brave! i would never have the guts.
Another question:
What happens if the senior thinks i'm starting something with his girl when she's the one flirting with me? Am i in big trouble then?
and this is where communication is key... don't assume anything of anyone; say it all! just make sure to that point across, that she flirted w/ you and not the other way around.
but what's this senior guy like? you can be the only one to judge since none of us know him :o)