From Legion of Super-Heroes Vol. 3 #8, in which a black speedo-clad Magnetic Kid goes swimming with Comet Queen & Laurel Kent. Tragedy strikes when Laurel is shot by an unknown gunman.
(Edit: Correction - I mistakenly thought this was Polar Boy, when it is in fact, Magnetic Kid, Cosmic Boy's brother. It's now been corrected. Thanks to an Anonymous reader for pointing this out!)