So I thought a fun little thread would be a neat place to post your favorite intentional and unintentional mistransformations Here I will get you started. My boss decided to try and transform the Generations Thrust on my desk and gave up almost done
I transformed my Takara Quickstrike for the first time without looking at the instructions. It wasn't until I posted the pic in the Beast Wars thread and Split Lip pointed out to me that the waist needed rotating. I give you Scorpionheadcrotchman Oh well, I guess it goes in and out the same end which must be easier since his robot mode head doesn't really have a mouth...
Stretch Primestrong! Sadly I may have just ended the thread Good Lord, what the heck was this designer not thinking!?
Blackarachnia's expression says it all. This next one actually isn't a mistransformation, but it's how Punch is actually supposed to be transformed based on his box art and instruction manual full body shot. Even so, it looks weird as all hell:
No pictures, and not funny, but for my AEC shelves, I purposely alter the robot modes slightly on the repaints so they look a little different if I can.