I hear a lot about the importance of honesty in relationships, but I'm a believer in telling kind or polite lies. Honesty can hurt sometimes, and doesn't always leave a winner, instead just making both parties lose. So here are the lies I think you should tell when dating.
1. Why you really have two cans of beer in the fridge, and who that t-shirt used to belong to. I currently have some left over beer in my fridge, which had been bought by a guy I briefly dated. I'll never drink it, but it would be wasteful to throw it away. So it will live in my fridge until I have a visitor who drinks beer. If that visitor ends up being a date, I'd politely lie and say I had it from a friend's visit, not a previous date.
2. When your last relationship was. This seems like a standard dating question, and I suppose people are trying to work out two things. Firstly, whether you are capable of committing and having a normal partnership with someone and secondly, whether you're rebounding or emotionally ready to meet someone new. I never ask this question, but I have been asked it repeatedly. I don't lie as such, but I refuse to answer on principle. People successfully find new relationships regardless of when their last one was. It's really an irrelevant fact, so I skirt around the issue as much as I can without seeming weird for doing so.
3. How many people have you had sex with. I found that I got asked this all the time in my early 20s, but never in my 30s, so I suppose it's the younger person's version of asking when your last relationship was. I've heard that women usually lie and give a smaller number, and men usually lie and give a larger number (ugh, hello everyday sexism), but now I'm older and wiser, I'd refuse to answer, should I ever be asked.
4. Who you were with last night. If you haven't had the talk about exclusivity or the status of your relationship, then you are merely dating, and may well be dating someone else. If you're on a dating site, you may well end up with two first dates in the same week. The polite lie is to never explicitly tell one date that you've been on another. A great example of a kind lie.
5. Why you are single. Again, this seems to be a standard first date question, and I think people mean it as a twisted compliment. I say twisted as your honest answer may well require putting yourself down. This is not the time for honesty, you don't need to confess that you had issues you were working through, or couldn't get over your ex, or cheated on your last partner. The polite lie is "I haven't met the right person," regardless of whether you really believe it or not.
As an extra bonus, here are two of the lies you shouldn't tell when dating:
1. What you're looking for from the date. Although I often giggle at some of dating profiles that explicitly state they are looking for a cheeky one night stand, I admire their honesty. If I'm looking for a relationship, it's extremely disrespectful to waste my time (and emotions) meeting me if you just want some night time fun. There is nothing wrong with seeking an "activity partner" as long as everyone knows what page they're all on.
2. Whether you're happy with how it's going. I once dated a guy for a few months, and eventually I had to be swallow my awkwardness and explain that I wasn't happy to still just be dating. I oddly felt guilty for needing/wanting more commitment, which is of course silly. He said being exclusive was fine, but the word 'boyfriend' wasn't. I gave it another month, but I quickly realised this wasn't enough, and I wasn't happy with where we were. There is no point moving forward if you're moving in different directions.