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...'"
Npc 1: 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
Based on the UK store name b&m bargains, popular for being cheap and "jippo" saying someone has "b&m broadband" states they have a rubbish connection and a cheap internet,
mainly when playing on a video game and lagging.