Hey kids, if youre getting bored during the Christmas Holidays why not try doing the James Bond undercover agent thing and send "secret messages" to your friends. There's a few ways to do this but the quickest and easiest way is to use Lemon Juice. Grab a lemon out of the fruit bowl, squeeze it into a small bowl, grab a cotton bud or small paint brush and start writing.
Once the "secret message" is done simply leave it to dry and then it is ready to send. Once the message has been recieved by the agent/spy he simply needs to heat the paper over a candle or even a hot light. Within seconds the secret message will appear (hopefully similar to the image above !)
This process can also be done in the same manner using milk or vinegar instead of Lemon juice. Have fun kids but be very careful not to overheat the paper as it may catch on fire. If you want to go real pro then you can also purchase invisible ink from Amazon !