Easiest way to get strong fast?

I don't know about the "easiest," it's a lot of work but lifting weights and dietary supplements will increase strength the fastest.

National Institute of Health on supplements:

http://www.ncbi.nlm.nih.gov/pubmed/10091274

try using crutches to walk for 2 months. That's how I got my self buffed up. But I am not quite sure if it will work for others