We speak of the outcome of a coinflip being heads or tails, which are surely singular nouns in this context, despite being derived from the plural forms of head and tail. So when we flip a coin twice and get heads (respectively tails) twice, should we describe the outcome as two heads (respectively tails), or two headses (respectively tailses)? I feel like you could make a logical case for the latter, but I guess the former does sound more natural?