I worked with a guy whose wife went through a difficult pregnancy. He had numerous afternoons where he begged to leave because of bleeding etc. All very supportive and we did a lovely big collection (the size of the place meant the collection was around £700) and cooed over his daughter when he brought her in.
Three months later he came in devastated. Wife was pregnant again and they were panicking about how they'd cope, but they couldn't face a termination. Again endless time off, early finishes and on numerous occasions he turned up with the original baby as his wife wasn't well. Everyone took turns of keeping an eye on her in the break room because he was so worried and scared about losing his job.
This went on the entire duration and then he announced (a week late which surprised people given the endless problems) they'd had another baby girl. Again congratulated, huge collection and everyone delightedly cooing over the photos. He promised to bring her in, but said his wife was very panicky over her as she was very small etc etc.
When the baby was a month old we had a new staff member start. In the staff room, in his earshot, she mentioned where she used to work. He walked out the room, left the site and didn't come back for a week.
Turned out the second baby was bullshit, he just realised how much time off he could get (it was very flexible and everyone covered for each other kind of place). He had planned to say she'd miscarried, but then one of our colleagues miscarried at work and he couldn't bring himself to say it. Amazingly he was allowed to keep his job! He didn't last long though as his colleagues basically refused to speak to him unless he returned the collection, which he didn't do.
The funniest BS story that turned out not to be was a colleague who said that her boyfriend was a F1 driver. No-one believed her, in fact some people were really really sneery about it and openly mocked her. Right up until she brought him to a wedding with her, and was then photographed in a magazine at a race.