When you take your leader's measurements, you realize they're too short, so you attach things to them to make the measurements more impressive. Attach some heels to the shoes, then attach another head on top of theirs. There — perfect measurements thanks to these attachments.

You have to remember the kun'yomi reading of this kanji, and the part you need to remember is つ. So, think of how you would attach something to something else. What would you need? You'd need two (つ) things to put together!