when you wake up so late in the day that you cannot call your meal breakfast or lunch but a mixture of the two is needed
the equivalent of brunch but not with tea and cakes and far less formal
i woke up uber late today so i went to the kitchen to make some lunkfast.
A meal taking the place of both breakfast and lunch. Unlike "brunch" which is usually a hearty, planned affair in a restaurant, lunkfest usually consists of fast food or whatever food is lying around the house, and is usually the result of sleeping in to the point where eating a separate breakfast and lunch would be impractical.
Guy: I overslept.
Other guy: That sucks, you missed breakfast.
Guy: Who cares? I can stilleat lunkfest.