I do this too, even have to touch things a certain number of times too. My fab number is four, nice, even number, so I especially like four x four too or 4444. I count to four over and over whilst chewing, brushing my teeth, washing my hands, make things add up to four or multiples of four. It's very annoying at times too though.

Like if I burn my hand under hot water I will have to put my other hand under for four seconds aswel. It can drive me mad to be honest. I shout things out alot and make noises and sometimes I even have to do that four times unless its been building up a while and I have to do it over and over until it's out of my system. I have ADHD too though n my psychologist said it's my impulses and obsessions.