OK here is the scoop from an older guy who has dealt with your question for himself.
There are two issues here, and they are both hydraulic. The first is volume, and the second is pressure.
In order to generate distance, you need to apply higher pressure to a substantial quantity of fluid because ...

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I wonder how she is going to get him to bear that. I suspect the incentives will be interesting...

Well since the idea seems to be to make the pleasure less pleasurable, a long time ago I ran across a free tool to control your tool that might play into this discussion.
On every plastic pop bottle there is a tough ring that is left when the lid is unscrewed that can be prized off the empty with a ...