omg sorry lisalisa but thats so funny! poor you, poor ds! you cannot make someone else retrieve the knickers- they might have to touch a sweaty gusset euccch! but you absolutely must get them. i think i would call the school and speak to receptionist and ask her to go and take the flask out of the bag and put it back for ds, and for her to hold onto the carrier with its contents til you can pick it up later, or get her to speak to ds and tell him to only take out the flask. not very inventive but might work.
everyone at school will know about this you know that dont you? everyone! it doesnt matter if he pulls the knickers out or not. if you try and get them back you will have to say why. and it will make the teacher's day in the staff room. they might pin them up on their noticeboard. there might be some pervy teachers wanting a sniff- they might end up on ebay