Theory:

     So you will understand, I trust, when I tell you how much I ache to be suave. I would love, just once in my life, to rise from a dinner table without looking as if I have just experienced an extremely localised seismic event, get in a car and close the door without leaving 14 inches of coat outside, wear light-coloured trousers without discovering at the end of the day that I have at various times sat on chewing gum, ice cream, cough syrup and motor oil. But it is not to be.
 
     Now on planes when the food is delivered, my wife says: “Take the lids off the food for Daddy” or “Put your hoods up, children. Daddy's about to cut his meat”. Of course, this is only when I am flying with my family. When I am on my own, I don’t eat, drink or lean over to tie my shoelaces, and never put a pen anywhere near my mouth. I just sit very, very quietly, sometimes on my hands to keep them from flying out unexpectedly and causing liquid mischief. It’s not much fun, but it does at least cut down on the laundry bills.
Explanation:
  
The narrator desires to be suave (meaning 'confident and charming') for once in his life. He might be good at greater or intellectual matters, but when it comes to the meagre and day-to-day matters, he may seem half-witted or imbecile.

The narrator wishes he could rise from a dinner table without looking like someone who had just experienced an earthquake. Or get in a car and close the door without leaving some inches of his coat hanging outside. Or wear light-coloured trousers without discovering at the end of the day that he got stains from chewing gum, ice cream, cough syrup or motor oil on his back.
 
vintage-1892037_640.png
The narrator wishes to be suave and have a normal life
 
The narrator's wife is particularly conscious of him eating while on a plane. When the food is delivered on the plane, his wife would ask their children to take the lids off the food for him, since it is likely that he would spill the contents. Or when he is about to cut his meat, his wife would ask their children to put their hoods up, as he might end up throwing the knife, meat or its residue on the kids.

The narrator says that the things are different when he is flying alone. When he is on his own, he doesn’t eat or drink. He would neither lean over to tie his shoelaces, nor would he put a pen anywhere near his mouth. He simply sits very quietly. Sometimes, he sits on his hands to avoid them from flying out unexpectedly and causing troubles.

Poor narrator, he always tries to turn into a stone when he is on a plane. He says refraining from doing anything cuts down on the laundry bills although it’s anything but fun.
 
Meanings of difficult words from the paragraphs:
  
S.No
Words
Meanings
1
SuaveCharming, confident, and elegant, typically used of a man
2
SeismicRelating to earthquakes or other vibrations of the earth and its crust
3
HoodsA covering for the head and neck with an opening for the face, typically forming part of a coat or cloak
Reference:
National Council of Educational Research and Training (2006). Moments. Accidental Tourist- Bill Bryson (pp. 56-59). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.