[robertpaulsen]

"This is cocaine", he said. He glances over to see the janitor listening in. "Just kidding, guys", he adds.

The janitor is expected to keep quiet about this?

[Know your rights]

"This is cocaine", he said. He glances over to see the janitor listening in. "Just kidding, guys", he adds.

Pure speculation ... and in any case it was not in fact cocaine.

The janitor is expected to keep quiet about this?

Red herring. The authorities are expected to not assume that jokes are meant seriously.