program help

i want to create a joke virus/program to use on my friends but dont know where to start.
i have a funny video and i want to the program on execute to play the video in full screen and loop the video. i want all user input to be disabled and create a startup key so on reboot its executed again. any help on where to start?

Locking this for the obvious reason: this knowledge can be also be used to make real malware.

More precise it is in violation of paragraph 8 section 6 of the Forum Policy:

Live Malware and possibly hazardous resources. Comodo is in the business of helping secure the internet, not distributing malware. These forums are not the appropriate place to attach to or link live malware (viruses, trojans, rootkits, etc) [b]and other resources that could be eventually misused for illegal purposes.[/b] In general, a link to the download site for 'malware' tests/demos and other 'proof of concept' applications are acceptable, provided they are not intended or designed to cause harm to a computer nor they could be possibly misused for other illegal purposes.