Fuck off.
I've been standing here for 8 fucking hours, going insane with boredom. Excuse me if I'm not grinning like a loon.
Why do people say this all the fucking time? Are you actually meant to just be smiling ALL THE TIME.
I once had to go to a toddler birthday party with a bunch of people I'd never met and after the 2 hours was up my face ached from all the fake smiling so like fuck am I doing that at work all day.

AIBU to think people(almost always men) should just stfu with their cheer up love, oh you look happy, it might never happen, bullshit?