A fungo bat is used by the coach to hit ground balls or fly balls to his team. All throughout high school and college many players use fungo bats to play fungo golf. This is when each person has a fungo bat and a baseball and they pick out targets around their field or complex and basically play it in the same manner as golf. Fungo bats should not be used to hit a pitched baseball because they are much weaker than normal bats and will break much much easier.

Once the basic bat has been turned, it has the manufacturer's name, the serial number, and often the signature of the player endorsing it branded into it opposite the wood's best side. Honus Wagner was the first player to endorse and sign a bat. Next, most bats are given a rounded head, but some 30%[citation needed] of players prefer a "cup-balanced" head, in which a cup-shaped recess is made in the head; this lightens the bat and moves its center of gravity toward the handle. Finally, the bat is stained in one of several standard colors, including natural, red, black, and two-tone blue and white.
If fungoes are a ball tossed into the air by a batter and then struck as it comes down then a fungo bat is a baseball bat used for hitting fungoes. To go into more detail, a fungo bat is a long, lightweight baseball bat used by coaches (or parents) during pregame hitting or practice to help them hit grounders and pop flys with more consistency and less fatigue. To be one of the best in baseball, countless hours of practice are a must and fungo bats are intended for both infield and outfield practice. Plus, they help tremendously with control and accuracy so that coaches and parents can place a ball where they want when they want. 

For starters, we should clarify just what we’re talking about when we say fungo bat. Longer, lighter and thinner than a regulation bat (but a larger barrel), a fungo bat is typically 35 to 37 inches long, and weighs between 17 and 22 ounces. As David Allison wrote in the June 1978 edition of Country Journal, “A fungo bat looks to be a cross between a baseball bat and a broomstick.”
Secondly, the first base fungo hits balls to the third baseman, who turns a double play with the second baseman to the normal first baseman, while the third base fungo hits balls to the shortstop, who throws to a shortened deep firstbaseman (this means that the deep firstbaseman stands closer to the shortstop than normal, so that the throw across this infield is the correct distance - this does NOT mean that the deep man stands any closer to the normal first base position - this length should always be sufficient)
Many players "bone" their bats, meaning that before games, they rub their bats repeatedly with a hard object, believing this closes the pores on the wood and hardens the bat. Animal bones are a popular boning material, but rolling pins, soda bottles and the edge of a porcelain sink have also been used. Pete Rose had his own way of hardening his bats: he soaked them in a tub of motor oil in his basement then hung them up to dry.[25]
Before we get started, we have to define the word "fungo" or "fungoes." To summarize, fungo (fungoes for plural) is a ball tossed into the air by the batter and struck as it comes down during practice sessions.  If you are a coach, you are more than likely familiar with a fungo bat. Or, if you are a player who has ever worked on ground balls or pop-flys in practice, you should know what a fungo bat is, as well. For the rest of us, a fungo bat might as well be a foreign object. What is that oddly shaped, extra long practice bat? So, let's answer the most common fungo bat questions:
There are many advantages to using a fungo bat. If you are a coach or a parent looking to improve your player's defensive skill set, you're going to want and need a fungo bat. A normal adult wooden baseball bat will weigh around 27-31 ounces, and after a couple of rounds of pop-flys, it is going to feel like you just went through a full-on workout. With the help of a fungo bat, you will be able to hit ground balls and pop flys all day without getting fatigued.  The barrel on a fungo bat will typically be 2 1/4 inches in diameter which greatly helps increase your control over the bat through the hitting zone. While the barrel has a much more thin diameter, it is also much longer in comparison to a normal wood baseball bat. This larger hitting surface and smaller barrel combine to give coaches and parents quick swing speeds with precise accuracy. 
Players can also create complex holes such as ‘two-part holes’ where the players must hit or reach one object before attempting to shoot at the hole. For example, a ‘two-part hole’ could consist of hitting the scoreboard first, and then once they have hit the scoreboard they must hit the ball back to home plate, that would be one hole with the player with the fewest strokes winning the hole. ‘Two-part holes’ are typically saved for the last hole in order to make things more complex and difficult on the leader.