Body language can often speak volumes, and the act of applying lipstick while making eye contact can convey subtle yet significant messages. Here's what it could mean:

1. Flirting: Putting on lipstick while maintaining eye contact is often interpreted as a flirtatious gesture. It suggests that the person is intentionally drawing attention to their lips and may be interested in engaging in romantic or intimate interactions.

2. Erotic Signal: In some cases, applying lipstick while looking someone in the eyes can be seen as an erotic signal. It may imply a desire for physical intimacy or suggestiveness, akin to the symbolism of oral sex.

3. Sign of Interest: When someone applies lipstick while gazing into another person's eyes, it can indicate a heightened level of interest or attraction. It's a subtle yet deliberate way of capturing the other person's attention and signaling romantic or sexual interest.

Ultimately, the interpretation of this body language cue may vary depending on the context and individual preferences. However, in many cases, applying lipstick while making eye contact can be seen as a flirtatious and suggestive gesture, signaling interest and potentially inviting further interaction.