there was manic laughter behind me , ahead the rite of spring thumping like an express train , and my only escape was a quick left turn into the toilets , there to find bobby and barney banging away on the floor , barney trying to whisper unqualified sweet nothings into bobbys ear while she squirmed away on the cold tiled floor , her skirt up to her waist and her knickers down to her ankles .