i am getting angry on the “s” of “bottles”, which has to be missing when there is only one bottle.
has anybody an idea how to get it done with few bytes lost?

it costs me 24 bytes!

" bottle"+"s of beer"[expr:]

where expr is an expression evaluating to zero or one.

's'[2 - bottles_on_the_wall:]
assert '' == 's'[2-1:]
assert 's' == 's'[2-2:]
..
assert 's' == 's'[2-99:]