My 2.11yo DS has been toilet trained for almost 10 months now...no 'accidents' in at least 5 or 6 months and quite content in doing his business swiftly and independently.
However he has recently started (past 2/3 weeks) attempting to have a sneaky wee in some unusual places...I've caught him standing at the back door pointing his groin area outwards in order to make a fountain of wee right onto the paving slab, in the corner of the garden, up against the indoor kitchen bin, balancing between a couple of sofa chairs...his bits dangling in the middle IYKWIM and the pee going straight on to our living room carpet 
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He knows his behaviour is silly, yucky and generally "not what big boys do" and when he is planning to do it I can see his eyes scanning to see that I'm not watching and afterwards he goes all sheepish and usually starts his next sentence with "I'm sorry Mummy but I did a naughty thing..."
Now fast forward to yesterday and the LO is at my parents for the day (they have him once a week when I work)...they tell me that DS asked if he could go and kick his ball about in the garden and within a couple of minutes he was back inside spilling to my Mother that he had weed and pooed outside. Mam saw him crouching down near a recycling bin and presumed he was just digging or playing with his pebbles...TBF her eye sight is a bit ropey these days. He was told off obviously...but they didn't dwell on the incident.
So I spent around 10 minutes last night talking to DS about the incident (before bedtime on his bed)...he promised not to do his business anywhere but the loo and I told him what a "big boy" he was for being so good, yadda yadda...I said that his older cousins are big boys who go to the toilet too...he idolises them so I thought this was probably the best approach seeing how this is something he is consciously planning and doing.
Anyway today I am working again (I work Mon/Tues) and he is with my OH. At about midday I receive a text saying "I was just about to take him to and he's done a wee all over my CD's...I don't know what to do!?" My OH is a bit OCD so I'm sure he's suitably fucking traumatised right now 
but seriously though, I just have no clue how to deal with this behaviour and I know I'm probably going about it all the wrong way.
Anyway needless to say DS has been 'punished', he didn't go to the soft play area and has been banned from any treats and television today...+ his much-loved bedtime story session. My OH is now worrying that he might be craving attention from us and maybe we are being negligent in this respect...I genuinely don't think this is the case but I would love to hear everybody elses take on the matter.
We talk openly about going to the toilet and don't treat it like it's a dirty process...I make a point of praising him on his toilet habits at least a few times a week and he's generally brilliant in this respect...I never have to prompt him for a toilet trip and he wipes (with assistance) and washes his hands. I just don't know what to do about his current behaviour and would appreciate ANY advice you have to give.
sorry it's such a long one!! (oor er)