Alright, then let me clarify ... normally I'm very careful to not sit on my phone, but it has happened numerous times with no incident.Have to say that made me laugh. You can't call sitting on your phone reasonably careful.
But I could see you might interpret what I said as "I was sitting carefully on my phone ...", which would be funny ("Hey Bob, are you crackin' a one-cheek-sneak, or are you sitting on your iPhone?")