Lisa Kudrow was actually pregnant in real life during this season, which is why the "Phoebe as a surrogate" storyline was created.
In a classic whodunit, the gang suspects the stripper stole the ring. After a tense "interrogation," they realize the truth is much grosser: The Duck swallowed it. [S4E22] The One With The Worst Best Man Ever
Phoebe is heavily pregnant with the triplets and is, shall we say, hormonal . Monica and Rachel throw her a baby shower, but Phoebe’s mood swings and the impracticality of "leather" maternity wear make for a hilariously high-tension party. Lisa Kudrow was actually pregnant in real life
After Joey's ring mishap, Ross decides to have both Chandler and Joey as his Best Men, proving that even with stolen rings and swallowed jewelry, the bromance is real. 🌟 Iconic Lines shall we say