For some reason, my Mac keyboard always thinks that the "t" key is always being pressed. However as you can see I can still type in the letter t, but it comes out delayed compared to the other keys. I think it is a software bug as the key still works fine, but on some pages the t key just gets spammed. Oddly enough, shift+t won't give me an uppercase t, but all the other letters work fine (and my caps lock has been converted to a backspace, so I can't test that (by choice)). this has happened before, but typically goes away after a restart, but this one time a restart didn't help.
Edit: Currently on Macbook Air (1 generation ago)