depending on the tone of voice used...usually used when you are really excited about something and you can't find the words to express yourself, use a high-pitched "meh." When you are angry or just feeling "meh," use a deep and weird sounding "meh." Or, when you just want to creep people out, say "meh" anyway you want, just say it really loud...and it's better when they aren't expecting it and you creep up behind them. then laugh really annoyingly.
MEHH!! HAHAHAHA hehehehe