Some guests are late

Wait 15 minutes, then start without them.

A guest breaks or spills something

Smooth over the incident and clean it up quickly.  The guest should apologize and offer to pay for damages—but if he doesn’t, chalk it up to the cost of entertaining a less-than-considerate guest.

A guest makes an ethnic slur or an offensive joke

Interrupt and change the subject, or ask for his help in another room, where you can tell him that his off-color jokes or remarks are making others uncomfortable.  Be sure to apologize privately to anyone who might have been offended.

Unexpected guests show up at your door

Greet them graciously and do your best to include them.  Set extra places at the table if possible (even if your place settings aren’t an exact match).  If all else fails, eat on laps in the living room.

A guest has had too much to drink

Cut off the alcohol and take away the car keys.  Offer him a place to sleep for the night or drive him home yourself.

There’s not enough food

Plate the food, using smaller portions of what’s short and larger ones of what’s in good supply.  Augment the salad, and add bread if possible.  Signal “FHB” (Family Hold Back) to family members.

Dinner is overcooked, undercooked, or an otherwise complete disaster

Laugh and order pizza!