Track 7 on Lep's "Pyromania" album. In some ways it's a typical hair-band power ballad with a clean arpeggio intro and verse that falls before a wall-of-sound chorus.
But this is also a good example of Def Leppard at their best. Their "On Through the Night" disc (for all its good points) sounds muddy compared to "Pyromania." Steve Clark, Pete Willis and Phil Collen's guitars stand out cleanly without dominating the sonic space (compare to Metallica's chunk-chunk-chunk bass-heavy guitar mix). The follow-up, "Hysteria," has comparable guitar sound, but sounds slick and overproduced.
"Foolin' " was one of the big hits on 1983's "Pyro," which seemed to hang around forever on the charts, offering hit after hit. I hated metal back then--and even I had to have this album!