Among the kinds of social gestures most significant for second language teachers, are those which are identical in form, but different in meaning in the two cultures. For example, a Columbian who wants someone to approach him often signals with a hand movement, in which all the fingers of one hand cupped point downward as they move rapidly back and forth. Speakers of English have a similar gesture, though the hand may not be cupped and the fingers may be held more loosely. But for them, the gesture means "goodbye" or "go away", quite the opposite of the Columbian gesture. Again in Columbia, a speaker of English would have to know that when he indicates height, he must choose between different gestures depending on whether he is referring to a human being or an animal. If he keeps the palm of the hand parallel to the floor, as he would in his own culture when making known the height of a child for example, he will very likely be greeted by laughter. In Columbia, this gesture is reserved for the description of animals. In order to describe human beings, he should keep the palm of his hand at a right angle to the floor. Substitutions of one gesture for the other often create not only humorous but also embarrassing moments. In both of the examples above, speakers from two different cultures have the same gesture physically, but its meaning differs sharply.