Growing up we ALWAYS dumped all grease into an empty coffee can. I was told it was so that the grease didn't clog the drains - but there may have been another reason too...as seen in this 1945 ad:
"Pass the Ammunition!
The fats and greases you save in your kitchen are ammunition when they reach the fighting front. Salvage every speck and turn it in to your neighborhood collecting center. Every drop of fat and grease is an important contribution to the war effort."
By the way....still, to this day, I pour grease into coffee cans...how about you?