Version using StringBuilder and without HTML tags (using new line instead of paragraph mark):
private static string LoremIpsum(int minWords, int maxWords, int minSentences, int maxSentences, int numLines)
{
var words = new[]{"lorem", "ipsum", "dolor", "sit", "amet", "consectetuer", "adipiscing", "elit", "sed", "diam", "nonummy", "nibh", "euismod", "tincidunt", "ut", "laoreet", "dolore", "magna", "aliquam", "erat"};
var rand = new Random();
int numSentences = rand.Next(maxSentences - minSentences)
+ minSentences + 1;
int numWords = rand.Next(maxWords - minWords) + minWords + 1;
var sb = new StringBuilder();
for (int p = 0; p < numLines; p++)
{
for (int s = 0; s < numSentences; s++)
{
for (int w = 0; w < numWords; w++)
{
if (w > 0) { sb.Append(" "); }
sb.Append(words[rand.Next(words.Length)]);
}
sb.Append(". ");
}
sb.AppendLine();
}
return sb.ToString();
}