This is more of a "what do you do?" rather than a "what would you do?" but anyway...
I was sorting through a load of DS's old clothes to pass on to a friend for her younger DS and came across a load of outgrown underpants. Would you pass them on too, or is that really minging? If not, what do you do with them? They are in good condition and if I had another child myself I wouldn't hesitate to pass them on to them but I don't and it seems a bit of a waste to just chuck them out. And sending to the chartity shop doesn't seem right either. 
Maybe I should turn them into bunting or something...