:-? Two parents encouraging teenage sons to portage approximately 2 foot square x 5 inch thick rock slabs out of Q, to use for their "patio" at home.  
:o Same group fills up the aluminum canoe at the end of the portage and go to push off, Mom is in front, not quite sat down yet.  Guys give the canoe a good push and it immediately comes to a complete halt on a submerged rock (we all know how well an alu canoe slides on rocks).  Mom is launched head first into cold shallow water onto a field of underwater rocks...not a word was uttered, I guess because of the shocked audience of strangers watching.