It was seeing the expression "I love Peter" that took my breath away. Usually, given that I am not the owner of one of the world's rarest Christian names, I would not have given this a second glance. But I was on a train dawdling for a moment by a platform shelter in deepest Bavaria; German graffiti writers were protesting their passions in English.
Before the train sped off again, I caught sight of another affectionate sentiment: "The day when I finished to love you is the day when I closed my eyes FOREVER!" The phrase "finished to love" clinched it for me. Clearly, no one had been organising package holidays for English graffiti writers abroad: the accurate spelling and the single grammatical error gave the game away.
Not all the messages daubed on the shelters and subways were so pretty. The concrete counter-culture had its share of hate as well as love, with a sprinkling of words like "fight back", "exploited" and "rage".
If you thought the public face of Germany - the fancy-cake coloured houses with their quaint pointed roofs and the cycleways full of healthy people - was the only face, then you would have to be prepared for a spray-can shock.
Yet the wonder was, whatever the sentiment, that these secret slogan scribblers should choose - in addition to the predictable material in their native language - to express their deepest feelings in the meanest places in a foreign tongue.
We all know from watching German politicians and celebrities interviewed on television that our language is second nature across the North Sea. It is as if they are putting back the clock 1,500 years to the days when our ancestors left their homeland to sail towards our shores and the two languages started to drift apart.
When we travel to the country ourselves, we find that it is not just specially selected interviewees who can do this. You speak to a shop assistant in faltering German and he or she replies in faultless English - without bothering to ask which country you come from.
You could argue that our home-grown graffiti writers, in their turn, are seeking to show an awareness of their Anglo-Saxon routes when they spell "love" as "luv", but you are bound to suspect that this is not necessarily through an intensive study of the works of Sweet.
Of course, our students' continental counterparts are doing some of their language learning outside the classroom with the aid of lyrics in the international language of rock music, but not all their proficiency should be attributed to the men and women behind the microphones from Britain and the US.
For all the talk of rising standards since the advent of GCSEs, this country continues to produce young adults who cannot write graffiti in their own language - let alone anyone else's. The real test of our success or failure is not to be measured by exam grades or passes. Read the writing on the concrete walls.
Peter King teaches English at Wisbech Grammar School, Cambridgeshire