I tested mine first. I pumped it while just holding it to see what kind of resistance it has and to see how big each pump makes it. Then I inserted it and just did one pump at a time waiting a full 10-20 seconds to make sure it was still comfortable. I live inflatable toys. Just not looking to rip for one.
If you test it first by pumping up to a certain size outside, it really shouldn't explode at the same size inside you. At least, not if you don't have heirloom watches and other rubbish up your arse too.