Ski-ing on water

A morning meeting in the middle of Düsseldorf, followed by a speedy trip to the next town along the river to get rid of the rather large paint mountain we discovered we were harbouring at the back of the garage. The normal recyclinghof wont take it but fortunately the one that does has outreach days, unfortunately my mini isn't big enough for the whole of the mountain, so now there's a small hill of paint buckets squatting downstairs.

Tomorrow is the 13th birthday of Little miss bossy, there will be cake, once I've made it that is...can you guess what the blip will be?