SPOILERS if you haven’t seen last night’s episode ofWith How I Met Your Mother set to wrap up this year, fans of the CBS comedy have been left to wonder when and how Marshall would administer the two remaining slaps he owes Barney, left over from a slap bet he made with him years ago. The gag has spanned seasons, every once in a while resurfacing as Marshall delivers one more epic slap — usually when Barney’s not expecting it. He was expecting it during last night’s episode, and the slap was pretty glorious. So glorious, in fact that the catchy song “You Just Got Slapped” was also revived, covered this time around by the great Boyz II Men at the end of the episode.If your memory’s rusty on the original song, it was sung by Marshall in the "Slapsgiving" episode and also released as a music video, which you can watch below:Given the tone and the way Jason Segel sings the song, I would’ve thought Neil Diamond would be the perfect guy to cover the song, but Boyz II Men’s soulful harmonization cannot be denied. Their cover took the song to the next level and is certainly worthy of its place among Slap Bet lore. Also your iPod. Yes, the cover is available on iTunes already!Last night’s slap almost fulfills the slap bet payback. As Marshall said at the end of the episode, he still has one more slap, and it wouldn’t be all that surprising if that slap was held back until some point in the finale, if not the final moments of the series. Given that it’s arguably’s longest running and best joke, that seems fitting enough. As fitting as dedicating a whole episode to the second to last slap.While we wait for the series to wind down to its final episode, which is set for March 31 , CBS has GIF-ified the previously administered slaps. Here’s my personal favorite:That’s Slap 6. You can view the others here