Oh god, I hate that analogy. xD
Mainly because my mom uses it ALL THE TIME. It's mostly when something requires me to spend money, due to something all my friends are doing. Like going to Naka Kon.
"Well, I dunno.. I figured I'd cosplay too, since my friends are."
"It doesn't matter what they're doing. What if they all went and jumped off a bridge? D<"
To me, it always seems like she overreacts when she uses that against me, and then I want to tell her to lighten up. xD;