Paramore and B.o.B. rock out for his birthday

After finally meeting at their 2010 VMA rehearsal in September, "Airplanes" hit makers B.o.B. and Paramore's Hayley Williams have been making surprise guest appearances at each other's shows every chance they get.

In late October, Williams shocked B.o.B. fans at Vanderbilt University in Nashville, Tennessee (her hometown), with their first off camera performance of "Airplanes."  Next it was in Dublin, Ireland where B.o.B. and Williams rocked the O2 arena. Finally, the duo hit up MTV EMA's in Madrid as guest performers (and Williams displayed her white wing pants).

Then, while performing in London this week, Paramore brought B.o.B. on stage during a performance of their hit "Misery Business" to wish him a happy birthday. Williams then conducted the sold-out crowd of 15,000 in singing happy birthday to B.o.B.

"This is my first birthday overseas, and it's the best time of my life," B.o.B yelled.

B.o.B., Paramore and a couple of lucky fans then commanded the stage by singing, head banging and dancing to the last bit of the song. Happy belated birthday B.o.B.!