roedhunt: I have a suggestion for you...
Wait until you and her are discussing different things. Weather, TV shows, life, etc etc... Bring up funny commercials. Tell her about one, then ask if she has a favorite. After she does, say "oh yea. I remember that one. That IS funny..What about that commercial with Michael Jordon in the Hanes underwear one where the women are guessing men's preference? My sister/mother/cousin loves that one..." After she responds to that, Ask "So do women REALLY do that?" She probably will say yes. Then laugh. If she says no, say "Yea I guess it would be hard to tell".
Now her thought is on you...Dont change the subject, just be quiet. 9 times out of 10 (just an expression), she will ask which one you prefer. There's your opportunity....
Reading the forums here, what I gathered, is that men who are big, either hang loose or wear boxers instead of briefs.
So, maybe say something nonchalant like.. "oh, I have to wear boxers/no underwear. Briefs are just too tight (or confining)...
If that doesn't give her a subtle hint.. I don't know what would.... Unless she's.... uuuh....slow...