A Regular Don Juan

Don Juan: A man who is an obsessive seducer of women.
son of a gun: euphemism for "son of a bitch" (a profane term for a man who is nasty, rude or otherwise offensive).

Falsies

falsies (colloquial): pads or breast-shaped forms worn inside a brassiere to make the breast look fuller.

Playing Post Office

Post Office (Wikipedia) is a kissing game historically played by American teenagers at parties.

Navel Maneuvers

In the Dog House

in the doghouse (slang): in great disfavor or trouble.
jackass: 1. a male donkey; 2. a stupid or foolish person.
serve one right: to treat one as one deserves, esp. to punish justly.

Keeping in Shape

in shape: physically fit.

A Little Behind

behind (colloquial): the buttocks.

Hot Dogs!!

dogs (slang): feet.

That's All...