Some years ago was enroute CMB-NRT and had told the CC to keep seated as the seat belt sign would remain on for awhile due to weather enroute for the first 30 minutes or so.
Unknown to me, about three minutes after takeoff, the CC in the aft cabin started service....and upon encountering severe turbulence, one whole drinks cart was turned upsidedown, resulting in many smashed bottles. Fortunately, no one was injured.
It pays to listen to 'd boss.
Some never learn.
