'A tiger? In Africa?'

 I think something we don't think about often enough is that cis people misgender other cis people all the time too, because cis people are really bad at guessing people's gender. This is because, it seems to me, people decide what gender to slot others into based on what psychologists call a schema - a sort of heuristic concept, not an ideal but a generalised notion of 'a man' and 'a woman' and maybe if they're very progressive they have a schema for what they think an enby looks like too. 

When encountering new people, they compare them to this schema and the more points of agreement with one or the other they make a guess. And this is where it comes unstuck, because there is more variation within the same gender than between genders. Which means tons of us, trans and cis, don't fit the schema most people use for 'woman', and vice versa. Think of all those butch cis women who keep getting hassle from the toilet police while they don't notice passing femme trans women because the latter ironically have more points of similarity to their schema.

The easiest way out of this is probably to just stop trying to guess and ask people, but (aside from, in Britain, the existential cultural horror of having to have a real conversation with anyone), the reason humans like to use heuristics and schema is that most of us are lazy bastards and resent having to use the massive brains evolution gave us (evolutionary psychology is a pseudoscience which tries to justify this laziness by saying we need the spare cognitive capacity to keep an eye out for a sabretooth tiger) and this, I feel, is one of the factors behind what we might call basic transphobia, as opposed to full-blown terversion: the resentment of intellectually lazy people at being required to be slightly less intellectually lazy (god knows how these dullards would cope with an actual smilodon but I'm guessing not well). 

This, of course, can metastasize into full-blown terversion when the lazy arse becomes obsessively resentful of trans people for the unpardonable crime of making their life slightly more difficult, which gradually develops into the profound sexual obsession with trans people that characterises that deeply unhappy character, the tervert (normal people do not have to take photographs of themselves in posh restaurants doing their best non-Duchenne smiles with the caption 'look how much happy funtimes we are having' to prove they're having a good time, great sesh photos just happen). Ironically their overdedication to not having to do a tiny bit of new thinking leads to their brains constantly overthinking in a way that makes them miserable. 

TL;DR transphobia is lazy, ignorant, and proves you're thinking in an outmoded way, possibly because you labour under the unconscious delusion you might have to fight a massive cat.