From Wikipedia: "They require a warm subtropical to tropical climate that is cool but also frost-free or with only very slight winter frosts not below âÂÂ4 ðC, and with high summer heat, rainfall, and humidity. " They need high humidity ... really high humidity. And acid soil Also, they may need cross-pollinating by a different variety ... "Isolated or single lychee trees will usually set acceptable amounts of fruit. However, recent research has demonstrated that under some conditions, cross-pollination among different cultivars may increase fruit set. Therefore, in some cases there may be an advantage to planting more than one variety. " Here is a link that might be useful: California Rare Fruit Growers

That's "trailing" raspberry. But you likely figured that out. (sigh)

The "banana melon" I grew last year had orange flesh and looked like a melon not a cuke inside. It was an heirloom variety melon. Was this the type your friend grew as well? I wouldn't expect the fruit picture to be an offspring of that if so. It does look rather squash or cucumber like in the fruit. Does your friend compost? FataMorgana

As this post is EXTREMELY old, I'm sure you've already either figured out how to get fruit from your lychee, or else chopped it down in a fit of rage because it never fruited... But for people with the same problem who are coming to look for the answer in the comments, it looks like your tree is out in the open (which is a bad thing). If it flowers and then the fruit never sets, it's likely because it is too windy for the tree. Lychees are notorious for fruit not setting unless you block almost ALL wind from it. If you look at pictures of lychee farms during fruiting season, every tree is covered in giant tents. You may have to put a similar tent over your tree when the flowers start to come out as well if you want the tree to produce fruit.