Often when cooking, you will brown some meat and drain off the grease before using the meat in some other application. 

This is an important service announcement.

Grease belongs in the garbage!  If you absolutely MUST pour it down the drain, run very cold water with it. 

I know what you’re thinking.  Shouldn’t I pour hot water to keep it liquid? 

Well, are your pipes hot all the way to the sewer?  No.  Running hot water will keep the grease liquid and allow it to collect together until BAM the pipes get cold.  The grease, all nicely collected now, will solidify exactly where you do not want it to.  In a clump, in your pipes.

On the other hand, by pouring the grease slowly and running cold water, you make little tiny grease droplets solidify.  Not much worse than running other solids down the sink.

But, please, just put the grease in the trash.  

Yes, my pipes are clogged right now, why do you ask? 

Apparently I needed to emphasize this rule in my own house a little more forcefully.