We've seen a lot of celebrity birthdays over the past week, but only one involved a present picked out by Miley Cyrus. Obviously, the lucky birthday girl in question was the one and only Britney Spears.The pop star was treated to a surprise birthday party hosted by her loved ones yesterday. The newly minted 34-year-old Spears shared photos of the festivities on Instagram, making sure to point out the special gift sent over by Cyrus. Those silver Britney balloons were obviously all Miley. To think, all we got the singer was this collection of GIFs Spears' sons were among those helping her celebrate at this charming little soiree.