I snogged Lesley Henderson (name changed to protect the...oh, okay, I forgot her real name) all the way through Wizard's 'I Wish It Could Be Christmas Every Day', at the school Christmas disco in 1974, under a piece of fake mistletoe (it was actually a bit of string, but you improvise, don't you? Lesley neither noticed nor cared - her strengths were not horticultural).
She only did it to make her 6' 2" boyfriend jealous, but the song elicits a nostalgic grin every time I hear it nonetheless. I was a legend for about a week.