Cute, but if we're at all talking about physical possibilities, the vagina comprised of muscles which - like any muscular group - needs to be exercised for whatever needs it can reasonably be expected to perform. In this case, stretching is key: as
cxx said, Jennifer has been "practicing" with artificial stand-ins so that she can move up to the MC's Thunderstick™ .
I've read that some parents even consider buying dildos for their growing daughters, to help minimize the chance of negative impacts when they attempt to have sex. That's not considered typical it seems (because people relate such active support to more nefarious implications?), but still gets at the whole need to be used to stretching those muscles if you want them to work more nicely for you.