Having a drunken smooch with a stranger on a night out is one thing, but carefully planning a rendezvous with someone while in a relationship with a different person is something else entirely.
It involves being much more calculating and coming up with ways to hide your intentions from your partner.
And according to the controversial dating site for married people, Ashley Madison, there's a whole secret language that cheaters use to avoid getting caught.
They've shared these codewords, so you might have a chance to work out what's really going on if, heaven forbid, you should ever find yourself in this horrible situation.
The first is known as "tinmanning" and it occurs when the person who is cheating, doesn't want to become emotionally involved with the person they're having an affair with.
Like the Tin Man from The Wizard of Oz, they're trying to remain heartless - because if they catch feelings for that person, they'll soon become "zippered".
There's also NSFS, which means Not Suitable For Spouse and is used when the person they are having an affair with sends them messages or photos they wouldn't want their husband or wife to see.
And those who eventually end up marrying the person they cheat with are said to be "stealing home".
But it doesn't stop there.
Holidays taken with the person you're cheating with are called a "straycation", while any jewellery gifted to the person might be referred to as "fling bling".
Meanwhile the term "silver spoon" is used when the person they are having an affair with is much older in age.
Speaking about the codewords, Isabella Mise, director of communications at Ashley Madison, said: "A successful affair is an undiscovered affair and discretion is our top priority.
"We've learned the ways in which our members carry out their affairs to keep them a secret, and we decided to give them one more - a language."