The last time I spoke to George Clooney
He seemed quite improbably puny.
I think it was him
’Cos he asked, on a whim,
If I wanted to meet Carla Bruni.

The ersatz celeb in this case seeks to draw attention away from his physical inadequacy by offering an introduction to a fellow star. Presumably he has an equally unconvincing Signorina Bruni waiting round the corner, primed and ready to pounce. Or perhaps he’s the real McCoy, just smaller-than-life?