Fifth house belongs to Jupiter and looks after fame, children and knowledge. Ketu although quite similar to Jupiter in spirituality differs a lot in personality from Jupiter. Jupiter is warm and welcoming while Ketu is cold and secluded. It goes without saying that Ketu feels uncomfortable in fifth house. 

     Fifth house looks after fame that an individual can get. Ketu isn't interested in fame nor does Ketu wish for approval of others. Ketu actually excels in anti-social behavior and feels pride in going against society norms. With Ketu in fifth house there is either negative fame or no fame. Fifth house represents children also. There are high chances of problems with pregnancy and progeny especially if the native is a female. Children born have anger issues and anti-social behavior. Most of the time they have a difficult life. Fifth house is also the house of knowledge. Ketu can give excellent knowledge regarding spirituality and Rahu's aspect can give knowledge of foreign languages. Natives can be fluent in many foreign languages if they try their hands at them. 

     With Ketu in fifth house there would be Rahu in eleventh house. Rahu's aspect on fifth house is great for stock markets especially for pharma, chemicals and hospital stocks. As long as native focuses on long term investment, Rahu's aspect should ensure native sees abundant and unexpected profits from time to time. Fifth house also looks after entertainment, social parties and get together, art exhibitions, political rallies and music concerts. Ketu hates any event of socializing so there is every chance that the native is a total bore  unless other factors in horoscope help. 

      Overall Ketu in fifth house is a bad placement for it. Its necessary to pray to Lord Ganesha if there are problems with pregnancy or children are way too rebellious. Children should also be taught to pray to Ganesha as he is the lord of wisdom. Ketu's anti-social and angry behavior can only be eradicated by prayers to Lord Ganesha.