The only question I have of Gladys is what the heck IS a pip?

You don't want to know what time she took the midnight train to Georgia?

Gladys Knight performed on Ted Mack's Original Amateur Hour in 1952 at the age of seven, winning first prize. On September 4, 1952, Gladys, Bubba, sister Brenda and their cousins William and Eleanor Guest began performing together during Bubba's tenth birthday party after a record player malfunctioned. Shortly afterwards the quintet agreed to form a group, under the insistence of Gladys' mother Elizabeth Knight. They settled on the name The Pips, inspired by the nickname of their cousin James "Pip" Woods.


Source: Wikipedia 

https://www.yahoo.com/music/blogs/hip-hop-media-training/why-did-gladys-knight-background-singers-call-themselves-191655418.html

Now you come to mention it... it is a bit odd to have called them the pips!  But those were odd times! That's my best guess :P

The seed of some fruits, such as the orange or tangerine. 

Seeds. When they went rotten, they left Gladys and joined Nick Cave.