Royal Mail has launched an investigation after a viral video showed workers in its Clapham office looking spaced out after eating "hash brownies" from an unclaimed parcel.
"Today almost all the posties in Clapham accidentally ate hash brownies and I had to pick them up one by one cause they were so high" was the message posted on the video, which has now been deleted.
"I think it's weed," one voice says on the video, which shows a box labelled "Edibles by Pablochocobar".
A spokesperson said: "Royal Mail expects the highest standards of behaviour from our people at all times. We are taking this matter very seriously.
"We have commenced an investigation which will determine whether any further action, including disciplinary action, might be taken.
It said it was also reminding all staff of the correct procedures for dealing with items with no address for delivery or return.