Thought for the week #2

[Team No Idea]

Following on from my last week's ramblings about cats and toast, this week i have come up with a tricky question that has baffled scientists for years! indeed NASA are looking at going to Mars in 2014 to try and find the soloution to this mind boggling question. .....
I thought i'd post it on here as you were all so quick in resolving my last "Thought for the week".............

How do "kEEP OFF THE GRASS" signs actually get on the grass ?????