A clitty is what many transwomen call their dangly bits… what men would call their penis.
The origins are from body dysphoria, feeling their physical characteristics do not match what their mind says they should look like. (Men’s genitals that should be a woman’s would be a common form of transwoman gender dysphoria.) Not all transfolks have body dysphoria, but plenty do, so instead of saying a person who, as a woman who was AMAB (Assigned Male At Birth), has a penis, the transwomen have renamed their body parts to fit their reality.
“Clit” or “Clitty” is a common term. There are other names: “Girldick,” “Outie,” “Strapless,” and there are still transwomen who will use the term “dick” or “cock.”
Each Person Names Their Own Body Parts
The deal is the person names their own privates. Do not assume; Wait until you know before using a term. Of course, asking about someone’s genitals as a matter of course is a rude thing to do, but if you are making out with someone… AFAB/AMAB/Cis/etc. it’s a good idea to ask them what they would prefer to call their privates. Then use their words, not yours or even ones you see here.
Most of all BE POLITE & RESPECTFUL. If it’s none of your business, don’t ask about it.