You will need a large piece of paper and a pen for this puzzle. You do remember how to use paper dont you :?: 
Connect all three houses to each of the three utilities without crossing the pipes :!:
+-----+ +-----+ +-----+
| oil | |water| | gas |
+-----+ +-----+ +-----+
+-----+ +-----+ +-----+
|HOUSE| |HOUSE| |HOUSE|
| one | | two | |three|
+-----+ +-----+ +-----+
Fifty Tokens to the first person to explain how to do it