The True master way to conceal a hit....

Items required...
1: any sort of piece you can take 1 hit out of and put out right away...
2: a soda with a straw...
3: lighter... duh

Step 1: take 1 hit... not too big, and put the piece out right away.
Step 2: hold for a few seconds, the slowly exhale hit into straw, through the soda.

if you do this slowly enough, the syrup from the soda will mask the smell. i must say that it did kinda taste like bong juice afterwards though.