"fun pastime" is correct and usable in written English. You can use it when you want to refer to something that is enjoyable and recreational. For example, "Playing softball with my friends is a fun pastime.".
And some might find the mix of real-life horror and a "fun" pastime uncomfortable.
Gardening as a fun pastime is popular among young people; careers are a different matter entirely.
I happen to have three adolescent sons and in this way recently learned about a supposedly fun pastime known as a "case race".
Without the option of watching a screen as something to do, our children learned to read for pleasure and see books as a relaxing, comforting and fun pastime.
Hateful remarks should never find their way into places that were created to be useful sources of information and fun pastimes.
Other fun pastimes include tearing through a shopping mall with a bazooka and taking out every store you see, allowing a mob of skinheads to surround you before exploding into a ninjistic fury that leaves them all dead and running in circles with an M-16 killing everyone (good and bad) that happens to be nearby.
In fact there is barely a prominent Democrat politican in American not engaged in their party's fun new pastime: Everyday Wal-Mart Bashing.
Being a terminologist, I care about word choice. Ludwig simply helps me pick the best words for any translation. Five stars!
Maria Pia Montoro
Terminologist and Q/A Analyst @ Translation Centre for the Bodies of the European Union