大姨妈如期而至

This is a humorous way of expressing menstruation has arrived on time. '大姨妈' (Big Aunt) is often humorously used in Chinese slang to talk about menstrual cycles. Thus, this online name might be for someone who wants to express the regularity or inevitability of an expected event with a bit of casual and light-hearted language that plays with taboos and common euphemisms.