Andy Murray, cheeky boy, he did an awesome one, hey, I'm Joe Suburbia with my bright yellow shirt and oakley sunglasses, I'm gonna try that in my match!
I'm playing a regular season boring doubles match, although line 1, so maybe that made it worse that it wasn't a high level match like I was hoping for. My partner and I are kind of cruising, up a break, and the better server of our two opponents is serving, having gotten out to an impressive 40-0 lead on his serve. He decides now is a great time to underhand serve, nets it, then double faults. I didn't care about the match that much until he did that, I become "re-engaged" and he loses his service game and they win 2 more games the rest of the match because that motivated me. Yes, I have poor mental strength, I play up when I care or the opponent is good, I cruise control to closer wins when I think the opponent isn't good enough to give me the match that I want, especially regular season.
So, just don't do the underhand serve. First, I'm never going to be standing as far back as the pros on serve and I am 6'4" so my reach is plenty long enough to get to the serve, so you aren't going to ace me, probably won't ace anyone else unless they are 3.5 and in double knee braces. If that is the case, then it is just shameful to do it, and I'm sure someone may come on and say they did it once, that's wonderful. Save it for a social game if you are playing with friends, but don't do it against strangers, the pros do it because of the new phenomenon of standing 6 feet behind the baseline to return serve, that's not your world.