Afternooner

[Ernesto]

Sexual intercourse during the [lunch] [hour] or [afternoon] hours.

[Kai]

A person who spends an afternoon engaged in a certain activity, or at leisure. Frequently with the relevant day specified, as Saturday afternooner, Sunday afternooner, etc.

[Sarah]

Someone who generally starts their day in the [afternoon], getting out of bed after 12pm.

It could be from [late nights] or just general [laziness]