Hi! here's some kinda of bug i've found a few days ago:

1. Change Object's prototype:

Object.prototype.somefunc = foo() {bar;}

2. Try to create an element:

var div = $('<div/>', {
	class: 'someclass'
});

3. Browser throws an Exception:

'TypeError: doc.createElement is not a function'

Reason for this exception is located at line 138:

if ( ret ) {
	if ( jQuery.isPlainObject( context ) ) {
		selector = [ document.createElement( ret[1] ) ];
		jQuery.fn.attr.call( selector, context, true );

	} else {
		selector = [ doc.createElement( ret[1] ) ];
	}

}

jQuery.isPlainObject return false on a object having it's prototype modified. In normal case jQuery should use document.createElement, but in case of abnormal return it uses doc.createElement instead.

p.s. sry for bad english