No these are not eggs to brood upon, these are used to throw at the enemy. Almost every kit has them, and they can be used for multiple purposes. Their main use is against the enemy ground personnel, favorably used for throwing around corners or over fences to announce your coming. Especially useful to eliminate those difficult-to-reach enemies.
But these holy weapons are also useful for a variety of other tricks. You can use them to clear a path through mines or claymores, or to distract the enemy. They are especially useful to throw into a vehicle like a jeep or transport helicopter. But this requires some skill and the grenade launcher is much more useful for this purpose. When you're feeling like having an S on your chest, you can also inflict some damage to heavier vehicles like an APC or a tank. But the damage will be minor and you'll draw unwanted attention to yourself.
Lastly there is a difference between the average left-click lob and the adjustable right-click. While throwing a grenade with the left mouse button will give you average pitch, the right-click allows you to adjust the throwing strength. The duration of holding the right mouse button down will allow you a variation between a left handed Miss Piggy pitch, and one that would even leave Babe Ruth flabbergasted.
Note: The longest throw possible can be achieved by using the left button and timing the release to occur at the top of a jump
Fragmentation grenades consist of a metal body and an explosive charge that is delayed after pulling the pin from 4-4.8 seconds. They can be thrown 35-40 metres and have a blast radius of 5-10 metres but the fragments can travel further and cause less serious damage. They can be very effective in urban surroundings most especially when clearing enemy held up in small areas such as rooms in buildings, however the use use a hand grenade in such circumstances does not garauntee all fatalities and caution should still be taken. 1)