Robin Thicke and his girlfriend April Love Geary took a night off from diaper duty to ring in his 41st birthday! A source revealed to Access that his guests all sang a rousing rendition of "Happy Birthday" before Robin himself hopped on the mic to thanks his friends for feting him. The West Hollywood hotspot also presented Robin with a 3-tier birthday cake, complete with sparklers! In one snap, Robin seems to be happily blowing out his sparkler candles while his ladylove looks on.