Ok so this is an easy one considering you have years to prep. Start by building a shed in the backyard. 15x15 will be a good size. When it is completed, start digging a large hole in it. Everyday for the next years just go out and dig a little more. Shore it up so it is safe and won't cave in. When he comes over, go out and show it to him. Tell him no one knows about it and you have not yet decided what to do with it.
Just have guns all over your house then take him on a tour of your house and act as if the guns aren't even there just show your house like you would do to a guess. You should put an AK in the frontroom, shotgun in the kitchen, 9mm in the bathroom, 380s upstairs in every room, and a clock 23 in the basement.
Pretend that your daughter is pregnant and get all happy and emotional welcoming him to the family. Works even better if they haven't started sleeping together yet.
I think you guys need to start thinking about scaring the little head and not the big head. Buy some medieval castration devices. Make a point of showing the boy your collection before the first date. The little head will think twice before losing his two best friends. I'm just saying ...
Is she white? Is the boyfriend a 6'3" latino driving a fake Cobra? If so you have no chance of stopping him. You're daughter and bathroom sink are doomed.
Wait till he comes inside with some groceries....hide against the wall....when he turns around....scare his as into oncoming traffic.
