fabulous, fabulist

Fabulous or fabulous means incredible or unbelievable, or, more informally, exceptionally good--
He told a fabulous story that involved abduction by space aliens and amnesia.
The new restaurant is fabulous; you should try it.

Fabulist or fabulist means someone who relates short stories with a moral ( fables ), or, figuratively, a liar--
Aesop is still the most famous fabulist in our literature.
Don't believe everything he says; he's something of a fabulist.

Now that you know that, you can say--
"He tells the children fabulous stories about his army days; he's quite a fabulist."