YES!! I am GLaD to say that I have made a Combustible lemon!! About a year ago I went to a surplus store and there was a box of decommissioned hand-grenades, they looked cool so I bought one. Then after playing Portal 2 and hearing about the combustible lemon, I remembered I had a hand grenade. My sister said she was going to the store to get some ingredients to make lemon bars, I asked her if she could pick up an extra lemon for me, she asked why and I just said, "It's for Science." I then constructed this, it is basically a lemon with the top of a hand grenade on it, I also stuffed an M80 firecracker inside so It would actually blow up!
Sorry that the picture quality is so bad, it's bad because I had to use a video recorder to take a picture of it.
*UPDATE* There is a video of this combusting, but it failed a bit because the M80 that was originally inside got all wet from lemon juice, so it isn't as big of an explosion as I hoped, but it's still cool: [link]