What you should not give a friend with no sense of humour
1. Rafflesia arnoldii, the world's largest flower, in Bahasa Indonesia called the Bunga Bangkai, from Sumatra. Bright red and beautiful, it is pollinated by flies, and because it is pollinated by flies, it stinks to the skies of rotting flesh.
2. Amorphophallus titanum, the Titan Arum, from Sumatra again. An unbranched inflorescence (the world's largest), not a flower. Again pollinated by flies, and therefore about as fragrant as a rotting horse. If your friend has a sense of humour, a very pretty thing to give.
3. Stapelia gigantea, in German the Aasblume, from southern Africa. The flowers are hairy, and stink of, yes, rotting flesh again.
It's a mystery to me why the world's largest flowers are also its most foul smelling.