Usually inappropriate toiletting is the first indication of a urinary tract infection. ESPECIALLY when they pee in the sink! So get him checked out at the vet.

Time for a vet visit !

How many litter boxes do you have? Rule of thumb is one more than the number of cats you have, so that means you need 3 boxes.

It could be that the youngster doesn't like sharing.

Good luck.

One stray kitten that I took in pee'd and pooped in the bathtub, right over the drain, for a couple of days. (At least it's easy to clean and sanitize a bathtub!) She was afraid of sharing the litter box with my other cat.

I did two things--I got a second litter box. And I scooped up her poop and put it in the box and then put her in the box with it.

After that, she started using the new box all the time. Eventually, she got to the point where she'd use both boxes, one for pee and one for poop.

I would limit access to both the clothes baskets and the sinks for this cat. And do have a vet check him out.

There's some useful tips at the link below.

Here is a link that might be useful: litter box issues

My cat went through a phase when she was about a year old where she peed in the sink all the time. I took her to the vet and even took a sample of the urine in (on a cotton ball) to the vet and they could not find anything wrong with her. She did it for a couple of months and then stopped as suddenly as she started. She was an only cat so the litter sharing was not an issue.

As far as peeing in the clothes, since she was a tiny thing she would do it every time she got in trouble. I got a tall hamper with a lid and make sure I don't leave clothes piled around anywhere. She is almost 13 and will still pee on an available pile of clothes if she gets mad. Best idea is to remove the opportunity.

I agree with adding more litter boxes. I had this problem with one of my two cats; it turned out that she hated the single covered litterbox that I had. I added another, open, one and no more problem. Do take kitty to the vet, and then try this route if she checks out ok. You may have to experiment with number, placing etc. for awhile but it is worth the effort. Make sure no clothes are on the floor and reduce all other opportunities (as KFarrel rights says above!)

We had a cat who would "go" in the wrong place if we had a house guest or there was some other change in her environment.

Has your kitten been neutered? If not, that might cause him to want to mark things with urine.

I agree that he might have a urinary problem. Besides infection, foods with a lot of food coloring or preservatives can be irritating to some kitties' systems.

I hope you figure out what's going on soon.