I have dribbled things onto my BB chinos, too. More than once, in fact...
If your chinos are a light color, take them to a good dry cleaner. It may take some skill to get the entire stain out without damaging the fabric and without leaving a ring, so you may not want to try to get the stain out yourself. Not all dry cleaners are created equal, so I do mean a "good" dry cleaner. If you don't have one you trust, your local BB or other men's clothing merchant may have a recommendation for you, or carefully read online reviews.
If your chinos are a darker color, you can probably get the grease out yourself. This is what I do:
I use a good stain-removing spray (I chose one based on a Consumer Reports article). Use a toothbrush or fingernail brush to work it in (gently) from both sides of the fabric, then wait a couple of hours before washing to let it work. Wash the pants in very warm water with a medium-sized load of other 'warms', including smaller items like t-shirts and underwear. Be sure to use a good detergent (see CR again...) The warmer the water, the softer the bacon grease, and the easier it is for the detergent to remove it. (The water ought to be warm-enough for you to shower in. Check your washer temperature at part-fill, set the machine for "hot" for a few moments if there's a need to warm it up a bit.)
Don't use bleach, it doesn't do anything to the grease and is harsh on the fabric.
After washing, examine the pants closely to see if the stain was removed. Don't dry the pants until you know for sure. If you still see evidence of a stain, you may need to try something a little more aggressive. Wash them a second time, but instead of the stain-remover, apply detergent directly to the spot (again with a brush) and let it work for a while. Consider pre-soaking them in a sink with relatively hot water. Although the care tag says "40 C" (which is 95 deg. F)., you can probably safely soak them at a higher temperature. (Note that if it's too hot for you to leave your hand in, it's too hot for the fabric and the finish.) My suggestion of a hot-water presoak is probably frowned-on by BB, especially since the care tag doesn't recommend hot water, however if the stain is really obvious you won't be wearing the pants again...so IMHO it's worth a try.
If there's still a noticeable mark, well, you can always wear them with a long coat......