You can also combine emotes for some interesting results. For example, use Ctrl+Shift+3 and just as your face turns red, cry or laugh! People may start recommending sunscreen! And don't worry; this effect isn't permanent.
Use the Emote balloon, available in the store for 250 credits, can be used for emotions that you want to keep on yourself for a much longer time. You can switch between emotes from this item's gold card. Keeping the "happy" version of this one on you permanently will probably have a negative effect on your multiplayer room popularity score, so keep it on something else most of the time!
And finally, if you really cannot hide your feelings or describe them with the above emotes, you can use the Love or Smiley Potion, which you can use for stronger (or more complicated, in the case of love) emotions.