I am ambidextrous

Yes, I am completely and totally 100% ambidextrous.

Not just a bit ambidextrous, or even slightly. I am perfectly ambidextrous. I can do anything with either hand - or foot. I have no preferences, and neither side is stronger than the other. I can, for example, put my knife and fork in either hand, kick things with either foot, and I'm equally accurate when throwing things with whichever hand.

Writing is a bit different. As left-handed people will know, writing is not best done using the left hand; this is because in the west we write from left to right, and the side of the hand tends to smudge what's already been written, so I write with my right hand - though I can equally write with my left hand, and both methods yield identical results (apart from smudges!) Of course, some nations write from right to left, and for these, left-handed writing is somewhat preferable. One trick, which comes naturally to me is mirror-writing. With my left hand I can mirror-write, going from right to left. You have to hold the result up to a mirror to read it, and it then appears identical to normally written words. I can, with some effort, write different things with both hands simultaneously, or normally with the right hand and the same thing mirrored with the left hand. Quite the party trick.

Generally speaking, about 10% of people are left-handed. It's not well understood why 90% of us are right-handed. People who use different hands for different tasks (mixed handed) or who use both hands with equal skill (ambidextrous) are uncommon. Only about 1% of us are ambidextrous. While this seems a small figure it does yield about 65 million ambidextrous people worldwide, though the 1% does not differentiate in the matter of the degree of ambidexterity - many of of those 65 million are probably just a bit ambidextrous. I'd like to think that true full ambidexterity lies in rather less than 1%.

In real life
What does being ambidextrous mean in real life? Day to day it makes little or no real difference. I rarely say to myself "I'll do this with my left hand I think". Choice of hand is an unconscious decision. However, some activities are clearly designed for the right-hander. Scissors, for example, don't lend themselves to the left hand as not only is there a squeezing force required, a lateral force is applied in order to keep the blades together, and the left-hander naturally applies this the wrong way, forcing the blades apart. (left-handed scissors are available!) My tin opener works on the right-hand side of the tin, meaning it can ony be used with the right hand turning the thing. I don't know if left-handed tin openers are available. All cameras are designed for the right-hander.

At best, ambidexterity is more of a party trick than a useful skill. People are fascinated when I switch the pen over to the other hand, or even pick up a second pen and start using both. I sometimes play snooker, and here ambidexterity is decidedly useful - I simply switch hands for those tricky shots, while normal people might need to use the rest.