"Scientists have discovered a pulsar (with an estimated mass of between 1.4 and 2 solar masses) traveling at an estimated 2.5 to 5 million mph (0.0035c to 0.007c). According to NASA's Chandra X-ray Observatory:
Originally discovered with the European Space Agency satellite INTEGRAL, the pulsar is located about 60 light-years away from the center of the supernova remnant SNR MSH 11-61A in the constellation of Carina. Its implied speed is between 2.5 million and 5 million mph, making it one of the fastest pulsars ever observed.
By comparison, one of the fastest man-made objects is the Voyager-1 spacecraft, currently traveling at an estimated 38,100 mph relative to the sun, or approximately 0.000056c (5.6 x 10-5 c)."
It looks like there isn't a solid explanation yet [wikipedia.org], but it certainly happens. IANAA, so if anyone who knows more about the subject would like to expound ...