Section 377

"Whoever voluntarily has carnal intercourse against the order of nature with any man, woman or animals, shall be punished with imprisonment for life, or with imprisonment for a term which may extend to 10 years, and shall also be liable to fine."

Explanation.
Penetration is sufficient to constitute the carnal intercourse necessary to the offence described in this section."

Section 377A

"Any male person who, in public or private, commits, or abets the commission of, or procures or attempts to procure the commission by any male person of, any act of gross indecency with another male person, shall be punished with imprisonment for a term which may extend to 2 years."

Our comment 

Section 377 potentially makes any sexual activity an offence except the insertion of the penis into a human vagina. It is based on the archaic Christian concept that sex is only for procreation. Pleasure is an illegitimate motivation for sex. Thus, any kind of sexual act that does not permit the possibility of conception, e.g oral sex, anal sex, even masturbation or sex with rubber toys, is "against the order of nature".

Section 377A broadens it further to encompass mutual touching, even a situation of "if you show me yours, I'll show you mine." Section 377A is specific to a situation involving males only.

In both sections, consent or age or majority is immaterial. Furthermore, the law applies even if the activity takes place in private.