Well, perhaps she has to do something embarrassing like singing in public. Since she lost the bet, she has no choice but to overcome her reluctance.
She might be reluctant because she didn't expect to lose the bet. For example, if it was a bet about a sports game and she thought her team would surely win.
Maybe the reluctant mom bet with her friend that her family could go a month without eating junk food. However, someone in the family caved and ate some. So she lost the bet. Now she has to host a dinner party for her friend as per the bet terms. It's a situation where she's forced to do something she was reluctant about due to the lost bet.
Maybe the son's friend made a bet with the mom about something like the son's academic performance. If the son achieved a certain goal, the mom would lose the bet. For example, the friend bet that the son would get all A's in a semester, and the mom didn't think it was possible. But in the end, the son did it, and the mom had to accept the loss of the bet.
She might have to do the dishes for a week.
If the mom lost a bet about her daughter not making the soccer team, but in the end, the daughter's disappointment led her to practice harder. And the mom, despite her initial reluctance, could see the positive side and supported her daughter more. So it ends with a stronger mother - daughter bond.
It's not really a matter of fault. The mom was just reluctant and underestimated her son's capabilities. But it's not her fault as she might not have been fully aware of what her son could do. And the son's friend was just making a bet based on his belief in the son. So no one is really at fault here.
Well, this is a very odd phrase. But let's say in a made - up world, the mom lost a bet to some sort of magical being. And the consequence of losing that bet was that she was 'impregnated' with a magical gift or power that she now has to carry and develop. It's not in the literal sense of pregnancy, but more of a symbolic 'carrying' of something new and challenging.
Maybe the mom bet on a local contest and lost. So she had to perform a song in public as a forfeit.
Perhaps they bet on a sports event. The son was really into a particular team and the mom thought otherwise. When the son's team won, the mom lost the bet. As a result, she had to let the son choose the movie for their family movie night.
Well, perhaps the girl lost a bet on who could run the fastest in a school race. She bet that she would win but came in second. As a punishment for losing the bet, she had to do the winner's homework for a week. She was a bit grumpy about it at first, but then she realized it was all in good fun.