Generic name for a sailor, used in a similar manner as "Joe Blow" or "John Q. Public". Example: "You're working on an electrical system without tagging it out, when along comes Seaman Schmuckatelli, who energizes the circuit and ZAP, you're fried calamari."
Just enough to get a taste. You know that time when the cake comes out and everyone rushes to rape every joyous crumb. And here you come out of your cave yearning for just one bite. One savory crumb and there's nothing left. But because you made friends with Natalie in accounting, she was kind enough to save you a slice. And that's how I met your mother.