As for me, here are some threads I found funny:
Forza Hang Out (specifically posts #99 by Snooty [January 2014] and #338 by NolDaMan [March 2014])
Soooo (May 2014)
I AM THE GREASTEST FORZA RACER EVER, SOON YALL WILL FIND OUT, (March 2015)
moderaters talking rubbish (March 2015)
[Mod Edit] Sunshine and Rainbows (August 2015)
Test (October 2015)
[ONI] Ōkami No Ichigun (Est. 2013) - Style Over Everything. Specialists in Street Legal (throughout 2016)
^Okay, not exactly ALL of the thread, but a lot of it.
Not much new then. (specifically post #12 by Alfa Scighera, July 2016)
Certain cars need to be buffed/nerfed in updates (and later games). (September 2016)
invisible cats in garage (November 2016)
Enough Porsche!!! (specifically starting at post #108 by Ti Hsien and ending at post #134 by Alan J T, June 2017)
#ForzaFriday 3/9/18 – The Dude Abides (March 2018)
When a Mustang is not a Mustang (August 2022)
Forum is messed up! (September 2022)
^I don’t know why I find this thread so funny… but I do.^
Series 32 Festival Playlist Preview (specifically starting at post #185 by wwwREXwww and ending at post #206 by AAORTA, April 2024)