Reasons why someone might seriously utter this phrase:
1) They were one of the guys, and they fancied the other.
2) They were a
friend of
one or both of the guys, and were pleased to see the
blossoming
romance.
3) Strange to relate, some women like to see men kissing. It's not as common as the
reverse phenomenon, but it's definitely there.
4) The rest of the
night really sucked.
The original WU here was a so-called parody, referring to
the highlight of my night was two girls kissing, but it got nuked. Juliet's superior work rules the day.