Concrete cylinder

Less than 100 cm from my front door is a concrete cylinder. Good to sit on when you make phone calls, since network coverage indoors transcends the appallingly bad. Doubles as a little chair for smoking for those who are using, since it is normally not allowed indoors. You can hide things under it, even though JR advertisements try to discourage you from it. However, today when I stepped outside, mind you, it was dark already and the temperature had just dipped below 30C, a Japanese boy was using it. Should I put up a sign, should I boggy trap it, or was mine slightly too direct KONBANWA enough to mark territory? He has left now.. good..