Giant Snow Cock
Mum’s on her way home, it’s been snowing so she might be in a bit of a shitty mood, cold and tired and all that crap. So as an adoring son it is only decent, no in fact it’s your duty, to build a giant snow cock to welcome her home.
Then her response when you tell her you’re putting a video of her reaction on YouTube will be one of maternal pride, a moment of bonding between the child-bearer and her offspring. This is the reason parents have children, for these special moments.