Exercise on a memory

One of my exercises that inspired me was where I had to recall a moment in my past and write it in the present tense.  I'm not sure what inspired me to write this piece, but here you go:

I'm really thirsty. I can still taste and smell the chlorine from the swimming pool water. The splashing and playful shouting of the pool downstairs is drowned out by the churning of the Slush Puppy machine. I think I want a red one. I feel water trickling from my hair down the back of my neck and my t shirt sticks to the still wet bits. I'm mortified as I have no money – I'm only 8 or so years old – and have always been told by my parents not to ask for things as it's rude. But I'm thirsty and Adam's mum, Felicity, has always been so nice to me. I stroke my throat, somewhat obviously, and find myself saying 'I'm thirsty'. I think I'm being clever: I'm not asking for anything, so I can't possibly be rude. This, I think, is a stroke of genius and I feel quite self-congratulatory. Pausing whilst wrangling her son, Felicity somehow manages to smile and scowl whilst saying 'if you want a drink you only have to ask'. For some reason my stroke of genius makes me feel ashamed as I mumble an affirmative and ask for a glass of water in self-punishment, not asking for the Slush Puppy I want because I've made Felicity feel bad.