This actually happened.
My aunt got married to my uncle back in my awkward tween years. My brother, 14 at the time, and I, a girl of but 11, were two of the youngest folks at the reception. We went with my dad; I wore a hideous-to-me-now purple flowered cotton dress with a mammoth lace collar. (What was I thinking?!) I wasn't really into dancing that much yet having only one junior high dance under my belt at the time. The DJ played some wedding classics and I did the mashed potato with my Pop-Pop and Grammy. Then, since it was my first real wedding as an almost-teenager, I didn't know to expect that all the single ladies were asked to gather on the dance floor. Being at that age where I started liking boys, I thought I counted as a single lady. I went out with my two older cousins and three ladies who were bridesmaids. We lined up on the fire hall dance floor while my aunt grabbed her tossing bouquet from the head table. The DJ explained that whoever caught the bride's bouquet was going to be the next to get married. As the drumroll track played, my aunt launched the bouquet up and it landed right in my range. I didn't even have to reach out for it. Shortly after, as my family gathered around me to congratulate me, I sat back to watch my uncle kneel in front of my aunt and find her garter. The DJ explained to my innocent ears that the single men were to gather and try to catch the flung garter. My cousins, my brother, and some random menfolk were all pushing and shoving in that jocular, masculine way. Up goes the garter into outer space, down it lands in my brother's hands.
Now, you are thinking, that's probably the end of the story right? WRONG. The DJ, who had no idea that this was my sibling, insisted on the putting on of the garter. BLARGH. My brother just shoved it over my shoe and on my ankle about which the DJ did not feel was appropriate enough and freely commented. I stood up and started to walk away feeling totally awkward by the whole event. However, the DJ insisted that we have a dance together. Seceretly, I think the DJ was plotting out some young romance blossoming for future wedding business; however, my entire family was mortified by the suggestive comments of the DJ. At this point, my merciful father went and told the DJ that we were brother and sister. I danced the rest of the night with the garter flopping about on my ankle, unhappy at the slightly creepy turn of events.
The DJ did not seem to pick up on any of the social cues that everyone was fairly weirded out by this scenario and that his inappropriate commentary clearly wasn't, well, appropriate. If this should happen at your wedding, have a family member immediately inform the DJ. A brother-sister dance would have been nice, but with the colorful chattering of the DJ, it went sour. He could have easily said, "It seems that we'll be having a brother-sister dance. Why don't we get all brother-sister combos out on the floor for a little Count on Me by Whitney Houston?"
Weddings. They have ups and downs; having your wedding coordinator or Maid/Matron of Honor help with the glitches will keep your reception a glorious and happy event. Determine in advance who is wrangling the DJ and any other staffers under your employ that evening. As a bride, you shouldn't have to deal with these glitches--make sure you rely on your wedding party and family!