If they are a trophy from the past, then he needs to move on and get with the present. Especially when it comes in the form of panties where sexual memories are brought back. And if he's keeping them handy (in his drawers) then that speaks for another thing. I would confront him about his reluctancy to toss them out. Tell him his hesitation makes you wonder, he needs to understand this. Use the words, "If the shoe was on the other foot" (My boyfriend ALWAYS uses that line on me!) Would he just let it go if you were hanging on to some exes boxers, or sleeping with some guys shirt under your pillow? I think not. He shouldn't be worried about awkwardness in getting rid of them. That's a poor excuse. No one has to know. He could just as easily wrap them in some toilet paper and shove them to the bottom of the waste basket. Done. But, I wouldn't let something like this slide. You're his girlfriend, you need to lay down the law when it comes to stuff like this. If he can't understand your feelings, then he's inconsiderate. Another girls panties, especially if he's reluctant to toss them, are not something to take lightly.