Definitions

Gravy: noun, plural gra·vies.
1.the fat and juices that drip from cooking meat, often thickened, seasoned, flavored, etc., and used as a sauce for meat, potatoes, rice, etc.
2.Slang.
 a.profit or money easily obtained or received unexpectedly.
 b.money illegally or dishonestly acquired, especially through graft.
3.something advantageous or valuable that is received or obtained as a benefit beyond what is due or expected.

Origin:
1350–1400; 1905–10 for def 2; Middle English gravé, gravey < Old French gravé, perhaps misreading of grané (compare grain spice) < Latin granātus full of grains. See grain, -ate1

gravy boat: noun a small dish, often boat-shaped, for serving gravy or sauce.

Origin: 1890–95

blog [blawg, blog]  noun, verb, blogged, blog·ging. noun
1.a Web site containing the writer's or group of writers' own experiences, observations, opinions, etc., and often having images and links to other Web sites. verb (used without object)
2.to maintain or add new entries to a blog.

Origin: 1995–2000; shortening of Weblog

Jon [jon]
noun a male given name, short for Jonathan or form of John

john [jon]
noun Slang.
1.a toilet or bathroom.
2.( sometimes initial capital letter ) a fellow; guy.
3.( sometimes initial capital letter ) a prostitute's customer.

not of course to be confused with

jawn [jon]
noun Slang
1. Anything and everything in the Philadelphia area.

In conclusion, this jawn is a blog created by someone named Jon that is in itself named for a vessel that can hold something valuable and advantageous,  ill begotten gains, or delicious thickened fat drippings.