fun vs have on

fun

• To tease, kid, poke fun at, make fun of. 

• Enjoyable or amusing. 

• Whimsical or flamboyant. 

• playful, often noisy, activity. 

• amusement, enjoyment or pleasure 

have on

• To trick or deceive deliberately; to play a prank on. 

• To have turned on (an electronic device) 

• To be wearing.