Yeah baby showers are the worst. Here's some ideas to get through it:
1. Wear something form-fitting to show off your non-baby carrying shape. This should make expectant mother feel even more like a beached whale.
2. Play games on your phone the whole time. Ideally, ones with a lot of sound effects.
3. Make comments about pregnancy belly that are barely compliments 'My God, you're HUGE!' 'Are you sure there's only one in there!?' 'When are you due? Today?'
4. Act disappointed if she shares the baby's sex 'Oh well, maybe the next one will be a girl' or 'That's too bad, boys are so much fun'.
5. Drink, get a little tipsy if possible. If there's no drinks served there, bring a flask.
6. If anyone asks something about 'when will it be your turn' go on on about how much FUN you're having without kids - you can stay up all night drinking, leave town on a moment's notice, sleep in until 10AM on weekends, etc. Ideally do this in earshot of expectant mother.
7. If you start to feel guilty about any of the above, see step 5. Rinse, repeat.