Alcmene and Ahalya - Victims of masqueraders Zeus and Indran

Alcmene - Wife of Amphitryon beautiful woman on whom Zeus had his eyes on.
One time Amphitryon left on quest against the Taphians and Teleboans.
Zeus disguised himself as Amphitryon and had intercourse with her for around 3 days.
 When Amphitryon finally returned to Thebes, Alcmene told him that he had come the night before and slept with her.
She later gave birth to Hercules, son of Zeus.

Pic from here

Ahalya - Ahalya is one of Brahma's beautiful creations. She was married to the hermit Gautama. But she remained a virgin even after marriage and lived in same house with her husband.
One day Gautama left to river ganges on his quest to take bath.The demigod Indran tried to deceive Ahalya and tried to consummate with her when Gautama was away. But she refused his proposal.

So, Indran disguised himself as Gautama and had intercourse with her.
 (Whether she cuckolded her old husband on purpose or was really a victim of disguise is still a million dollar question.)
Gautama on his return from his bathing ritual in Ganges(river) came  to know about this, immediately became infuriated.

He cursed Indra to become a mutant with 1000 vaginas(???!!) and with no balls.
Later after plead from Brahma it was reduced to 1000 eyes.
 So, the curse from have 1000 whispering-eyes was reduced to 1000 eyes.
He cursed Ahalya to become a stone because she even being a virgin was expected to distinguish the scent of her husband from another male.
 Her curse was to be absolved if Rama stepped on her during his exile in forest.

Moral of the story: Try chastity belt on your wife and carry the key with you.

Check more comparison mythology stories here