Placing the temperature probe in a 6.5lb Boston Butt

Just stick it in the thickest part and try to get the tip right in the middle, you will feel if you hit the bone, if you do just re-position until you don't hit the bone.

Wait a few hours before you put it in to make sure the surface is above 140* so you don't take a chance of pushing any bacteria deep into the meat.

I always wipe my probe with alcohol right before inserting it also.