Coin toss

It's just the way the expression is used.

There's really no rule.

Saying 'head' or 'tail' would accomplish the same (making a choice);

Check out: http://en.wikipedia.org/wiki/Heads_or_Tails

I understand! Thank you so much, John.

I don't find any historical explanation of why the plural is used.

I always assumed it was a childish thing.

As children, we often played "odds or evens" with marbles. The designation refers to the number of marbles a player is holding in his closed fist, often behind his back. The concept is clearly singular, but young children always use the plural, sometimes sa

Language is not always logical, thanks, Avangi!

I wonder if the original was not a plural at all, but a possessive.

head's or tail's

I say it will land [on the head's side / on the tail's side].

CJ

That's a possibility! Thanks, CJ.