Does anyone deliberately mis-transform any of their toys? This could refer to just one small placing of a body part to achieve a preferred look in contrast to what instructions say. In some cases it could even have been intended by the designers but never documented for consumers. It however tends to fall short of a full desire to invent a fan mode.
Here are a few I or my brother did over the years (our collections were once in effect one collection so some of the toys I refer to I do not myself own).
G1 Optimus Prime (1984): Placing Roller on back of robot as a kind of low-slung backpack.
G1 Jazz (1984): Swinging doors back behind robot, as per cartoon look. Nowadays, I have to resist the desire to do this with mold-mate Stepper.
G1 Ratchet (1984): We used to combine both modules to achieve a taller robot mode. The rear tracks would be angled to form the feet of a vertically oriented medical bay and the smaller robot legs would fit in around the area of the front track. This would give Ratchet a huge bustle-like skirt out behind with the launcher emerging from it. We did a similar thing with Rodimus Prime. I've never seen images of this online, but surely others must have done something like this too.
G1 Grimlock (1985): Would sometimes angle his leg-hip parts to make the robot mode a tad taller.
G1 Megatron (1984): Sometimes positioned his gun barrel in robot mode like it is in the cartoon. This can be done but always feels a little awkward.
G1 'Coneheads' (1985): You know what we did. I think it would be more interesting to find fans who (a) did not or (b) gave the Conehead treatment to the other Seekers.
G1 Onslaught (1986): Would not fully extend his legs, because it did not seem fair that he was taller than Hotspot.
And now moving onto more recent times and a live-action toy...
Scorponox (as Michael Bay apparently spells it): I rarely put this live-action 'Zoid in all but name' into robot mode, but when I do I give it an ape-like posture, with all four limbs touching the ground. It just looks less naff.
And finally some Generations...
Victorion: One kind of kibble I quite like is wheels, so Rust Dust as breast plate has those half back wheels showing.
Overlord: I place the jet plane nose-cockpit piece on the robot's chest, pointing downward, rather than on the arm. I just feel this achieves a more 'Transformerly' look.
Trypticon: Not sure if this is a mis-transformation, but I've deliberately not placed those golden stickers on his eyes. Admittedly, I've used very few of those stickers because my patience and hand-eye coordination refused. But even if I could be bothered, I would not cover those lovely trans-orange peepers.
Over to you.