I like the picking up rubbish thats great idea.
Also school project on graffiti is a good excuse if your that kind of age.
I use the BUTCH BUTCH come here boy as soon as you see guards or security cops what ever as soon as they come up to you they all ready herd your calls for a dogs name and you can look real sad like you lost your beloved pet.Or go up to them first and ask before they ask you.
Say to them have you seen my dawg man ? they will be like no what dose it look like make sure you have a discription in your head Doberman red collar or some shit.
They usualy tell you to get lost keep calling the dogs name out as you leave
Another time I was on the tracks and got pulled up I said I was robbed on the train and these guys threw my bag out of the train around here somewhere have you seen it ?