Given the following context:  Practical Pig, Fiddler Pig and Fifer Pig are three brothers who build their own houses with bricks, sticks and straw respectively. Practical Pig warns his brothers to build their house with "War Savings Certificate" bricks so that the house will be a solid defence against the marauding Wolf. Fifer and Fiddler ignore him and continue to play, singing "Who's Afraid of the Big Bad Wolf?". As they are singing, the Big Bad Wolf in Nazi swastika regalia, attacks the two spendthrifts, and blows Fifer's straw house down. Fifer manages to escape and hides at Fiddler's stick house but the Wolf also blows it down. The two pigs run and hide at Practical's brick house. The Wolf then tries to blow down the strong brick house (losing his clothing in the process), but is unable to make much progress as the bricks have made a strong foundation. Finally, Practical Pig chases the wolf away in a flurry of bricks that unerringly hit the Nazi marauder in his rear. The three pigs then sing "Who's Afraid of the Big Bad Wolf?" but with the caution that their house has to be in order to keep the wolf away. A pastiche of war scenes follows, each of which ends with a message, such as an aircraft shooting out the message, "Invest in Victory". Other messages show the importance of spending less, and lending savings to create the weapons of war. Purchasing war savings certificates, are sold in a "Five for Four" arrangement,  answer the following question:  What are Fiddler and Fifer doing when the Wolf attacks them?
singing