It's not my work but my brother has talked about one of his colleagues who seems quite odd.
He collects the free metro newspapers on public transport and apparently has piles in his office, and when asked to tidy them away covered them with a tea towel and left them.
He searches bins and skips looking for hidden treasures, and my brother said he tried to kit the canteen out with 'new' cutlery he'd found round the corner. He also brought a scarf along to work and gifted it to a female colleague, and when she asked why it was dirty and wet it was revealed he found it in a puddle.
And maybe the strangest and most worrying thing - he keeps news articles about terrorist attacks and natural disasters in his drawer at work.