An inadvertant push of brakes during the taxi is something you'll never want to do.I did that in my initial 737 training,I wanted to taste the feeling of the braking action so I asked the instructor captain if I can do the braking for once.He said OK but even though I tried to be gentle my inexperienced feet did a terrible job and for a moment it felt like the airplane hits to a wall.So I learnt it the hard way.
Its better to keep the heels on the floor as perfectly explained by "Notsofantastic"