What is "to laugh out of the other corner of the mouth"

Laugh \Laugh\ (l[aum]f), v. i. [imp. & p. p. Laughed (l[aum]ft); p. pr. & vb. n. Laughing.] [OE. laughen, laghen, lauhen, AS. hlehhan, hlihhan, hlyhhan, hliehhan; akin to OS. hlahan, D. & G. lachen, OHG. hlahhan, lahhan, lahh[=e]n, Icel. hl[ae]ja,W Dan. lee, Sw. le, Goth. hlahjan; perh. of imitative origin.]

1. To show mirth, satisfaction, or derision, by peculiar movement of the muscles of the face, particularly of the mouth, causing a lighting up of the face and eyes, and usually accompanied by the emission of explosive or chuckling sounds from the chest and throat; to indulge in laughter.

   Queen Hecuba laughed that her eyes ran o'er.
   --Shak.

   He laugheth that winneth.
   --Heywood's Prov.

2. Fig.: To be or appear gay, cheerful, pleasant, mirthful, lively, or brilliant; to sparkle; to sport.

   Then laughs the childish year, with flowerets crowned.
   --Dryden.

   In Folly's cup still laughs the bubble Joy.
   --Pope.

   To laugh at, to make an object of laughter or ridicule; to make fun of; to deride.

   No wit to flatter left of all his store, No fool to laugh at, which he valued more.
   --Pope.

   To laugh in the sleeve, To laugh up one's sleeve, to laugh secretly, or so as not to be observed, especially while apparently preserving a grave or serious demeanor toward the person or persons laughed at.

   To laugh out, to laugh in spite of some restraining influence; to laugh aloud.

   To laugh out of the other corner of the mouth or To laugh out of the other side of the mouth, to weep or cry; to feel regret, vexation, or disappointment after hilarity or exaltation. [Slang]