Jewish law requires that secondary rules be placed around the primary law, to reduce the chance that the main law will be broken. As such, it is common Jewish practice to restrict the use of the word Adonai to prayer only. In conversation, many Jewish people will call God "HaShem", which is Hebrew for "the Name" (this appears in Leviticus 24:11). Many Jews extend this prohibition to some of the other names listed below, and will add additional sounds to alter the pronunciation of a name when using it outside of a liturgical context, such as kel or elokim. Many Jews also write "G-d" instead of "God". While this last substitution is by no means required by religious law (only the Hebrew name, not the English, is holy), it is done to remind the reader of the holiness attached to God's name. (N.B.: Some Orthodox rabbis, e.g., Shlomo Ganzfried, have held that none of the proper names of God should be erased, blotted out, or discarded, even in translation.)
English translations of the Bible generally render YHWH as "Jehovah" in several locations, while replacing the name altogether as "the LORD" (in small capitals), and Adonai as "Lord" (in normal case). In a few cases, where "Lord YHWH" appears, the combination is written as "Lord GOD".
I stand behind the thoughts expressed in my previous post; the language can probably be argued over. The belief is that the name itself has power and is holy.
Rather than P_t_r, could I call you, "He of the big feet and nice kitchen"?
Cheers,
Scott.