A combination of lunch and supper. When you skip lunch because you are busy or out and about and then get ravenous and eat after 2pm such a big meal that you aren't hungry again and so skip supper. Example: I was so busy working I didn't have time for lunch but I ate a huge lupper at around 3:30.
LUPPER
Meaning of LUPPER in English
Slang English vocab. Английский сленговый словарь. 2012