They say that curiosity killed the cat, however what they forgot to mention is, that curiosity also gets your mail opened!
Well lumpy mail that is.
So, what really is lumpy mail?
It is a letter, or small parcel which has something which is lumpy in it, (make sense I suppose) to encourage the recipient to open it. The lumpy bit is normally a promotional product or a small gift. Which could be a branded pen, a chocolate bar or seeds for example.