Jewelry, specifically as a sign of affection. You know, like "My husband loves me sooooo much, look at this rock he got me for our anniversary!" This is mostly because my sister and my niece use my mom to bankroll expensive jewelry because "we want something with memories that'll last!" It's disgusting that they take advantage of her insecurity just because she has money, and the worst part is Mom KNOWS they're using her.
Re: What is something that people often buy or do to show off...
So. uh. Yeah. Jewelry.