Beyonce sent Jay Z and the rest of the world a not-so-subtle signal during her concert Saturday night ... strongly intimating Hova was unfaithful to her.
Bey was performing her song "Resentment" -- all about being lied to and cheated on -- and she tweaked a few words to make the whole thing sound SUPER personal.
She tweaked the lyric, "Been ridin' with you for six years" and changed it to 12 YEARS. Not coincidentally, she's been with Jay for 12 years.
Then she changed the line "Like I couldn't do it for you like your mistress could" ... to "Like I couldn't do it for you like that wack bitch could."
Not clear why the change to "wack bitch" ... but the sentiment was clear ... being with someone for 12 years who was cheating on you. The crowd got the message and roared.
Rumors about possible infidelity have been surrounding the couple since TMZ posted the infamous Solange elevator fight video ... it certainly could explain why she was so mad.