The nominal function of "bob" was one of Bill's favorite linguistic jokes. It is essentially a replacer noun that phonetically masks another noun whose identity must be determined by the context. It functions phonetically to mislead, confuse, or throw the recipient off-guard for humor, and it usually occurs in response to a recipient's question. Often "bob" is used in place of a word that shares a phonetic property (such as beginning with b-consonant or the o-vowel as in dog.) And although there is a high probability that "bob" will mask a noun that it has already masked in the past, Bill could spontaneously adapt it for any noun occassion.
Examples
1) Proper Noun
Most often as proper noun it means "Bill".
X: "Hello, who is this?"
B: "Bob" (meaning "Bill" a.k.a. "L.L. Cool-J")
2) Noun
X: "Can you give me your email address?"
B: "Yeah, it's LLcoolJ at yahoo dot bob" (yahoo dot com)