My 20 week ultrasound! Advice please?

My ultrasound tech said the same thing at 20 weeks, so I asked again at 27 weeks and the guy said he was 100% sure it was a girl, I would go ahead and buy girly things and keep receipts! But its never 100% sure, I believe there are more cases of people saying its a girl and it ending up being a boy, my friends sister everyone thought was a boy because she always had her hand between her legs during ultrasounds and she came out a girl! 80% sounds good to me go for it! :)