Only smart people can understand a sarcastic joke like that.
Only intelligent people will understand the irony of a joke like that.
ーOnly smart people can understand a sarcastic joke like that.
「賢い人だけがそのような皮肉な冗談を理解できる」
smart people で「賢い人」
a sarcastic joke で「皮肉な冗談」
ーOnly intelligent people will understand the irony of a joke like that.
「聡明な人だけがそのような冗談に含まれる皮肉を理解する」
intelligent people で「聡明な人」
irony で「皮肉」
ご参考まで!