Because a new survey has proved that 57 per cent of Brits have admitted to this very thing - and 45 per cent of those were women!
The Ann Summers Great British Pleasure survey also revealed that lovers aged 35-44 are most likely to fantasize about someone they know rather than a sexy celeb.
But although this sounds shocking - and a bit hurtful - chartered psychologist and self-help expert, Dr. Pam Spurr says fantasizing isn't a bad thing.
"It is completely normal to fantasize about someone else during sex because the human mind is incredibly creative. With fantasies, you can roam into erotic territory involving anyone from a celebrity to a neighbour," she explained.
"It's a reality in life that sometimes sex becomes routine. However, by injecting your fantasy into your sex life, it can boost libido levels and revive the excitement and lust with your partner."
Although the bedroom is clearly seeing a lot of action, the 3,000 Brits questioned were enjoying many other places too.
Other than the 42 per cent who claim to keep their lovemaking in the boudoir, the results showed that a quarter of us regularly raise the temperature in the shower too.
A further 15 per cent have got it on in the workplace, nine per cent have had a fumble in a public place, seven per cent have admitted to doing some extra exercise in the gym and a shocking two per cent have even got away with a quick fumble in a church!
The results also showed that 40 per cent of Brits admitted that 'sex with an ex' was their top guilty pleasure, followed by role-play, bondage, watching porn and a threesome.
Wow - turns out we've really lost our stiff upper lip!
By Anna Patterson
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