The best way to find a gift that your friend will love is to think about her personality, sense of humour and the sorts of things she enjoys, as well as the sort of friendship you have with her. Once you've done that it's just a case of browsing through some products and imagining how she would respond to each of them.
If you don't know what sort of humour she has, which is unlikely if you're buying her a gift, then something safe and generic will be fine; otherwise, if she really is your friend you probably know whether she'll appreciate something silly or not. It's similar for the type of friendship you have; if it's a close one then you'll have a good idea what sort of thing she'll like.
It's worth considering if this is just a fun gift for both of you or whether you're trying to make a point. If it's just for fun then go with something safe and light-hearted; if you're trying to get a message across then make sure you do it in the right way!
As for the type of gift, whether it's something decorative or functional really depends on what she's like and what she's into.
With most people, it feels very special when someone buys them something that is specific to them and shows that they've paid attention and thought about it. This does mean getting something that's relevant to her as an individual rather than just any old novelty thing. Of course most people will enjoy receiving something funny but if that's all it is then it doesn't feel so special; however, if it's relevant to her personally then it'll feel much more intimate and meaningful.
Having said that, I guess most people would be happy with any kind of funny gift, but it's always nice to go one step further.
I'm guessing though that you're looking for something very generic though because you're reading this article which is designed to be generic. The best way to do this is just browse through some generic gifts and imagine how she would respond to them; I'm sure you'll find something suitable.
