Confidence Pills are special Context-Sensitive items. They unlock Conker's
ability to fully swim.
The confidence pills are gained inside the sewers of Poo Cabin after it is flooded, because Conker cannot swim (and uses yellow floaties). He must find a way to exit, when Conker sees a B Pad he uses it to pull out confidence pills, he then drinks them in a glass of milk, his floaties magically disperse and he then gains confidence and the ability to fully swim underwater.
From then on Conker gains the ability to swim, which is very important to complete the game.