Why laugh? Change but the name, and the tale is told of you.
 
[Quid rides? Mutato nomine de te
fabula narratur.]

Horace (65-8 BC) Roman poet, satirist, soldier, politician [Quintus Horatius Flaccus]

Satires [Saturae, Sermones], Book 1, # 1, “Qui fit, Mæcenas,” l. 68ff (1.1.68-69) (35 BC) [tr. Fairclough (Loeb) (1926)]
    (Source)

After the Miser scoffs at the story of Tantalus.

Latin sometimes given as "... fabula de te narratur."

(Source (Latin)). Alternate translations:

Takynge but his name,
This tale maye well be toulde of the, thou arte the veray same.
[tr. Drant (1567)]

Do you but change the name
Of you is saide the same.
[tr. Florio (1603): Montaigne, Essays, Preface]

Why laughst thou Miser? if thy name should be
A little chang'd, the Fables told of thee.
[tr. A. B.; ed. Brome (1666)]

What dost Thou laugh? and think that Thou art
Fool change the Name, the Story's told of Thee.
[tr. Creech (1684)]

Wherefore do you laugh?
Change but the name, of thee the tale is told.
[tr. Francis (1747)]

You smile, as if the story were not true!
Change but the name, and it applies to you.
[tr. Howes (1845)]

Why do you laugh? The name changed, the tale is told of you.
[tr. Smart/Buckley (1853)]

Well, why that laugh? but change the name, and the then the story's told of you.
[tr. Millington (1870)]

Laughing, are you? why?
Change but the name, of you the tale is told.
[tr. Conington (1874)]

You laugh? Well, just change the name and you'll find that this story,
as a matter of fact, means YOU.
[tr. Palmer Bovie (1959)]

What's so funny? Change the name and it's you
the myth's about.
[tr. Fuchs (1977)]

You laugh? Change
The name, and it's your story too!
[tr. Raffel (1983)]

Why laugh? Change the name of the fable
and it applies to you.
[tr. Alexander (1999)]

What are you laughing at? Just change the name and the joke's on you.
[Source (2002)]

You laugh? Change but
the names and this old story's about you.
[tr. Matthews (2002)]

What are you laughing at? Change the name and you're the subject
of the story.
[tr. Rudd (2005 ed.)]

Why do you mock him? Alter a name and the same tale
Is told of you.
[tr. Kline (2015)]