Interpretations:The Bright Side
upside down (backwards actually)
When you're done turning everything upside-down then we'll all just wait in silence and fear what's next
I really thought this was a song about positivity and depression. Then I got to the verse about a number 5 on a fire truck and realized that this could really be about a person stuck in a burning building. Conversely, wrapping it back in on itself, it may be about a person with depression being likened to being in a burning building.
The fire is blinding and the sound of the fire alarms keeps ringing. Everyone is staring up at the person trapped in the burning building not out of judgement but wishing they could save them.
The crowd is singing "You're a busy bee" either to try to encourage the person to keep trying to get out or maybe the person trapped inside was an arson who started the fire and is now reaping the results of their "business".
what happens next
I think the Bright Side and the ringing bells refer to the idea of heaven and jubilation and great things that await us when we die (but it's a white lie). If you work hard (busy bee), so we are told, you'll be rewarded in the afterlife. The crowd, the masses, are the believers. Religion is their opioid.