Even if your sentiments are genuine, talking about all those sleepless nights you spent worrying that your sister or best friend would never find The One is incredibly embarrassing. It's even worse if you pose it as a joke. "I could always rely on Sara for a last-minute Friday night out -- I knew she'd be available!"
If you want to make jokes during your toast, make sure they're actually funny. They shouldn't be thinly veiled insults. And may we remind you, talking about how you never thought the bride would never get married is a moot point -- now she is! Instead, tell the bride and groom how happy you are they found each other.