Getting bigger?

I had to answer the call of nature this morning after breakfast. John was in there washing his cereal bowl and mug.
Yesterday I had noticed him pouring his cereal into his bowl when I got in and had asked him "What are you having for breakfast?"
Before John could answer, Andy shouted over "Everything by the look of him!"
Back to this morning. I had entered my cubicle and doing my business, while John had finished his washing up and gone to the urinal. I'm not sure if he was at the urinal or was over at t he mirror when I heard him say to himself (I think) "Oh no I think it's grown."
This was followed by a second "Blimey, it has as well."...which I'm fairly sure was said looking in the mirrors by the sinks.
It has remained a mystery what he was talking about, or how big it had grown.