Mary J. Blige and Toni Braxton Rocking Out to Bell Biv Devoe

No one can resist getting down on the dance floor when Bell Biv Devoe starts performing "Poison" -- not even Mary J. Blige and Toni Braxton!

It all went down at a birthday party last night for Toni's brother-in-law, music producer Vincent Herbert. In addition to working with Mary J and Toni, Vincent has also worked with Lady Gaga ... who we're told was also in attendance.

Those girls are poison.

Poison

Bell Biv DeVoe (now in their early 40s) resurfaced at a NYC concert this weekend, looking snazzy.

Their first album "Poison" is credited with ushering in the "New Jack Swing" sound of the early '90s.

BBD's last album came out in 2001.

Bell Biv DeVoe: 'Memba Them?

In 1990, former New Edition members Michael Bivins, Ricky Bell and Ronnie DeVoe ruled the charts with songs like "Poison" and "Do Me" as Bell Biv Devoe. Guess what they look like now!