Because some people can only think out loud, and they don't want the radio to bother them while thinking...
If you do not nail the lids in a traditional coffin (read: cheap), the weight of the dirt will make the lid crack and your beloved will be buried in dirt inside their coffin.
This I looked up on Google, I guess historical definition has more than one definition of practice, the most common definition being exercise or rehearse...
Definitions of practice on the Web:
a customary way of operation or behavior; "it is their practice to give annual raises"; "they changed their dietary pattern"
exercise: systematic training by multiple repetitions; "practice makes perfect"
drill: learn by repetition; "We drilled French verbs every day"; "Pianists practice scales"
translating an idea into action; "a hard theory to put into practice"; "differences between theory and praxis of communism"
avail oneself to; "apply a principle"; "practice a religion"; "use care when going down the stairs"; "use your common sense"; "practice non-violent resistance"
the exercise of a profession; "the practice of the law"; "I took over his practice when he retired"
carry out or practice; as of jobs and professions; "practice law"
knowledge of how something is usually done; "it is not the local practice to wear shorts to dinner"
rehearse: engage in a rehearsal (of)
http://wordnet.princeton.edu/perl/webwn