yeah, i thoguth about it some more and I think partly it is his humour - he loves to pull my leg with outrageous stories of what supposedly happended in day care or supposedly is permitted there or what was served for lunch (snails and worms sauce is a favourite). Actually also i think sometimes he covers his embarrassement at discovering that he is doing something I do not approve of by saying but we do it at day care.
but i do plan to ask them but now we are on holiday. i think what he is talking about is that at day care he and his mates frequently go and pee together, which then i assume can evolve into playing (who aims farther kind of competitions). as i know the care givers quite well i think they would tell me if there was a problem but when we return i plan to speak to them. also this is only the fourth week he is without diapers (his choice and i am celebrating!! he does great and we have virtually had no accidents at all) and it roughly coincides with when the penis play during nursing began - obviously access is easier without a diaper.