Be it that bunch of roses we did not expect, or a thoughtful gesture like a surprise candlelit dinner.
But have you ever thought of surprising your partner with good sex?
For couples stuck in a routine lovemaking rut, nothing can ignite the flames of passion faster than taking your partner by surprise.
But where can you surprise your partner with sex?
We spoke to author of the steamy memoir The 251 Bet, Molefi Malepe, who says that one has to be very sly about the where and when of surprise sex.
"You firstly have to be creative about surprise sex. This is not to say you should have sex in a church, for example, but the old routine of removing your robe and joining your partner in the shower is not really a surprise, because they expect it. So if you are going to treat your partner, make sure that it is good."
Having said that, Malepe says it is important to be careful about your escapades.
"Try not to be too bold in your attempt. Sitting on your partner's lap in a club may get you arrested for public indecency, for example.
"Surprise sex works better if you ease your partner into it. Perhaps give them a call beforehand and be as sexy as possible, just to gauge their mood.
"You know your partner; if they sound irritable, preoccupied or stressed, rather save the thought for another day."
Malepe says these are the top spots that are ideal for surprise sex:
We all know the classic trench coat manoeuvre that we have seen in the movies.
Malepe says depending on your partner's position, you should do the same if there is no threat of violating company policy or being caught on camera.
"That move does not really work if your partner does not have an office of their own, for example, or works behind a desk in an open plan office.
"But this is not to say you still cannot surprise them with sex. In that instance, surprise sex works better if you randomly call them to offer to buy them lunch.
"Tell them that you were in the vicinity, and just decided to surprise them with lunch. Then park your car in the underground parking lot, (every office has that secluded spot where no one parks), and seduce them there. They will be thoroughly surprised."
Next, Malepe says, if your partner does have an office of his own, it is important not to announce your presence at reception.
"Pretend you are a client or something, so they don't expect you.
"If the receptionist knows you, ask them to tell your partner a little fib about who wants to see them.
"After making your way into your partner's office, lock the door behind you and have a go at it.
"It is so much sexier if you don't waste time exchanging pleasantries or discussing if you remembered to take the clothes out of the washing machine. Just immediately go at it."
For surprise sex at home, Malepe says one needs to be very creative, as the home is your and your partner's home base for sex.
"There really isn't much you can do to surprise your partner with sex at home because that is where they expect it the most.
"But a great idea is to be the dinner on the table, literally. Call them and inform them that you are making a very romantic dinner for the both of you.
"Then go all out setting up. This means set up the table and cutlery, bring out the wine glasses and even the candles.
"Next, dim the lights, and just as they are about to walk in, plant yourself on the dinner table. The idea is that you are the romantic dinner you were talking about on the phone. Then sit back and watch the sparks fly."
Malepe says this involves role play, and works best if you're having supper at a hotel's restaurant, and particularly well if your partner has an imagination.
"Excuse yourself as if going to the bathroom, and proceed to call your partner from there. Here is where the role-playing comes in: you are going to tell your partner to ditch that partner they are with (referring to yourself), and meet you in room so and so. They will initially be confused, but insist.
"Run up to the room and get down to your bare necessities, and proceed to ravage your partner."