Possible Clues:

• Pop star whose name used to be spelled with a dollar sign
• "We R Who We R" singer
• Singer with the #1 hit 'TiK ToK'
• Singer with the 2010 hit "We R Who We R"
• Musician who once changed the middle letter of her stage name to a dollar sign, but later changed it back to a boring old 'S'
• One-named singer whose name used to be spelled with a dollar sign
• Singer with the 2009 hit 'Tik Tok'
• "Blah Blah Blah" pop singer
• Word in many Bugs Bunny puns
• Gaga contemporary