What ancient and old fashioned slang phrase should make a comeback?

Jinkies.

When referring to young people, you should call them whippersnappers...

The bees knees

Cats pajamas

Balderdash

Great Jupiter's cock

Stone the flaming crows, how am I supposed to think of something like that at no notice???

Outta sight and in the groove

23 skidoo

[b]Blooming Ada ![/b]

[b]Poppycock ![/b]

Zounds

"Twenty-three skidoo !!" And we'll be able use it again in a few short years.