The actor - who plays Liz Lemon's (Tina Fey) boyfriend Criss on the NBC sitcom - told CNN that he studies the news so as not to miss any of 30 Rock's culture references.
"[I feel] the need to keep up in order to maintain the water-cooler talk," Marsden quipped.
Marsden went on to describe hotdog vendor Criss as "a dope, but a loveable one". He added that he's not sure how much longer he'll be appearing on 30 Rock given Liz Lemon's "track record" for ruining relationships.
"It's [Tina's] sandbox, but she lets us play in it," he teased.
Alec Baldwin recently announced that 30 Rock will air its second live episode on April 26.
30 Rock is broadcast Thursdays at 8.30/7.30c on NBC.
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Watch Weird Al Yankovic's 30 Rock cameo below: