The holy Ruzhiner would not tolerate any melancholy or even bitterness - and as a result, his chassidim became quite playful. One Tishah BeAv they spent some time tossing burrs at one another. Then they decided to run up to the roof of the beis midrash and lower a noose over the entrance. Whoever walked in the door could then be lassoed and promptly hoisted up to the roof. The prank succeeded until, sure enough, who should walk in but - their Rebbe, the Ruzhiner. From their vantage point it was hard to tell one hat from another, and only when the tzaddik was halfway up did they identify him.

When they had lowered him to the ground, he exclaimed, "Master of the Universe! If Your children do not observe Your Yom Tov, then take it away from them!"

Sefer HaMinhagim Chabad, English ed., pp. 98-99