this stands for : be my bad boy be my man be my weekend lover but don't be my friend. It stems from the lyrics of the song 'Bad Boy' ~ Cascada. It became a widespread trend within the Gacha community using the format of "'It's always but never b.m.b.b.b.m.m.b.m.w.l.b.d.b.m.f...'"
Npc1: bro its always 'I wuv you lovebug but it's never b.m.b.b.b.m.m.b.m.w.l.b.d.b.m.f...
Npc 2: Girl wtf i just asked about how your day went
Standing for “bottle cap”, b-cap implies something is subpar or not of the best quality; imperfect. It evolved through localised slang before spreading further across the world.
It can also be used as a cleaner way of saying “bs” or “bullshit”