Suppose, my dear, that you were I 
 And by your side your sweetheart sate; 
Suppose you noticed by and by 
 The distance 'twixt you were too great; 
Now tell me, dear, what would you do? 
 I know--and so do you. 
 
And when (so comfortably placed) 
 Suppose you only grew aware 
That that dear, dainty little waist 
 Of hers looked very lonely there; 
Pray tell me sooth--what would you do? 
 I know, and so do you. 
 
When, having done what I just did 
 With not a frown to check or chill, 
Suppose her red lips seemed to bid 
 Defiance to your lordly will; 
Oh, tell me, sweet, what would you do? 
 I know, and so do you.
Eugene Field
http://www.poemhunter.com/poem/suppose-2/